350 



FOREST AND STREAM. 



pcrcns 1, 1853. 



existence. This is not the place for the discussion of the 

 purely scientific aspect of this question as already ably dealt 

 with by Dr. Brandt, Patrick Geddes and Geza Entz and others, 

 and we will therefore only notice their researches in so far as 

 they appear to have a bearing upon the origin of the green 

 color of the. oyster. 



Entz has discovered that he could cause colorless infusoria 

 to become green by feeding with green palmellaceous cells, 

 which, moreover, did not die after the death of their hosts, 

 but continued to live, growing and developing within the lat- 

 ter until their total evolution proved thern to be forms of very 

 simple microscopic green algte, such as Palmetto,, Glceocystis, 

 etc., etc. My own observations on some green-colored infu- 

 sorial animals have, been of so interesting a character that I 

 will here describe what I observed iu a green bell-animalcule 

 IVorliciRa ehlorostdgma). Upon investigating their structure, 

 I found that next the cuticle or skin in the outer soft layer of 

 their bodies known as the ectosarc, at all stages there "was a 

 single stratum of green corpuscles very evenly or uniformly 

 embedded. In another form (Stentor), as already noticed by 

 Stein, the same superficial layer of green corpuscles was ob- 

 served, reminding one very forcibly of the superficial layer 

 of chlorophyll grains observed in the cells of some plants, as, 

 for instance, Anacharis. Now, it is well known that certain 

 animalcules are at times quite colorless and at others quite 

 green; this appears to be the-case "with Ophrydium. In this 

 last case I have a suspicion that vegetable parasites may be 

 theeauie of the green variety, but as for the others, Stentor 

 and Vorticella, I am not so sure that their green forms are so 

 caused. In them the superficial positions of the green cor- 

 puscles and their behavior toward reagents, leads me to think 

 that they must be regarded as integral parts of the creatures 

 in which they are found. 



A grass-green [.lunarian worm (Convoluta schultzii), found 

 at Rdsc.off by Mr. Geddes, was observed by him to evolve oxy- 

 gen in large amounts, like a plant, and "both chemical and 

 histological observations showed the abundant presence of 

 starch in the green cells, and thus these planariaus, and pre- 

 sumablv, also, Hi/dm, Sa&ihffitta, etc., were proved to be tndy 

 vegetating animals." While, some organisms, like the forego- 

 Ujfc appear to have true chlorophyll grains imbedded super- 

 ficially in their own substance, others, like the mdiolarians 

 some siphonophores, sea-anemones and jelly-fishes, harbor 

 true vegetable parasites, or preferably, vegetable guests. 



That the green observed iu a number of animal organisms 

 is of the nature of chlorophyll, or leaf green, has been proved 

 by Lankester by means of the spectroscope. A. W. Bennett, 

 in alluding to Lankester's observations, says: "In all cases 

 the chlorophylloid substance agrees in having a stron^ absorp- 

 tion band in the red— a little to the light or left— auS, except 

 in Idotea, in being soluble in alcohol, and in having strong red 

 fluorescence, and in finally losing its color when dissolved." 



The vegetable organisms which have been found to inhabit 

 the lower forms of life alluded to in the foregoing paper have 

 been regarded as belonging to two genera, which Dr. Brandt 

 has named Zoucldorella and Zoa.vanthwa, and which are 

 probably in part synonymous with the genus Philozoon, after- 

 wards proposed by Mr. Geddes. The latter gentleman, how- 

 ever, claims to have first demonstrated the truth of the view 

 that the yellow cells of radiolarians and polypes are algte; 

 secondly, tho foundation of the hypothesis of the lichenoid 

 nature of the alliance between algffi and animal into a theory 

 of mutual dependence ; and thirdly, the transference of that 

 view from the region of probable speculation into that of ex- 

 perimental science. 



Hitherto no one has apparentlv noticed the occurrence of 

 green vegetable parasites in bivalve molluslcs except Prof. 

 Leidy, who has very kindly permitted me to use the facts 

 observed by him relating to Anodon, one of our common 

 fresh-water mussels. In this animal he some years ago 

 observed what must be considered to be algous parasites. He 

 found them in great numbei-s infesting the tissues of the 

 mussel and of a larger size than the nuclei of the cells of the 

 host, in which they were embedded. They were also pro- 

 vided with a nucleus, and were, therefore, not a part, of the 

 animal, but a distinct vegetable organism. These facts 

 observed a long time since, render it very probable that Prof.' 

 Leidy was one of the first to notice the "intracellular parasit- 

 ism of a plant in an animal. 



The green color of the oyster as far as my experience goes 

 is not intense, as in many green animals, such as we. observe 

 in Stentor, SpongiHa, Hydra, etc., but is a pale pea-green tint. 

 This has been found to be the. color of affected natives os well 

 as of foreign ones, the gills and mantle being usually most 

 distinctly tinged. Exceptionally the heart 'is affected, its 

 color sometimes being quite intense. 



In studying some oysters which were obtained from Eng- 

 land through the kind offices of Messrs. Shaffer and Black- 

 ford, in response to a request coming from Prof. Baird, 

 certain ones were found which were decidedly green. Of 

 these the French Specimens of Oatrea cditUs, "and a very 

 singular form, labeled "Anglo-Portugese," had the gills 

 affected, and in some of. the latter the liver, heart and mantle 

 were very deeply tinged in certain parts, so much so that I 

 decided to make as critical an examination as my resources 

 could command. 



Spectroscopic investigations gave only negative results, as 

 it was found impossible to discern any positive evidence of 

 chlorophyll from the spectrum of light passed through chin 

 preparations made from specimens of green-tinted oyster, 

 some of which, like those made from the heart, are decidedly 

 green to the miked eye There was no absorption noticed at 

 the red and blue ends of the spectrum, such as is observed 

 when the light which enters the slit of the. spectroscope first 

 passes through an alcoholic solution of leaf-green or chlo- 

 rophyll, indeed, the spectrum did not appear to be sensibly 

 affected by the green substance which causes the coloration 

 of the oyster. No attempt was made to test the matter with 

 the use "of alcoholic green solutions obtained from affected 

 oysters, as the former arc not easy to get with a sufficient 

 depth of color, because of the relatively small amount of color- 

 ing matter present, in the animals. Unstained preparations 

 were used in all of these experiments. 



Finally, in order to see if the color was due to the presence 

 of some green compound of copper, Professor H. C. Lewis, of 

 the Academy of Natural Sciences of Philadelphia, kindly 

 made some delicate tests for me, using small dried fragments 

 of an oyster very deeply tinged with green in various regions, 

 especially in the ^\n', connective tissue and mantle. The 

 fragments were burned in a bead of microcosmic salt and 

 chloride of sodium on a clean platinum wire in a gas flame: 

 this test did not give the characteristic sky-blue name which 

 should have been developed had there been the minutest trace 

 of copper present. 



It is therefore clear that the substance, whatever it may be, 

 is not a corrosive metallic poison derived from copper, which 

 if present would almost undoubtedly be detected by a peculiar 

 acrid metallic, taste, which woidd be experienced when one 

 ate such oysters. In making some practical tests as to the rela- 

 tive qualities of such oysters as compared with whito-fleshed 

 ones, opportunities for which were kindly furnished me by 

 Mr. J. M. Carley of Fulton Market, I failed to detect the 

 sligheat difference of flavor. Such also is Professor Leidy's 

 vci diet, who Informs mo that he made a similar experiment, 

 and a restaurateur with whom I discussed the matter, de- 

 clared that he was in the habit of selecting them for his own 

 eating, preferring their flavor to that of the white oysters. 



It has been objected that the green color could not.be de- 

 rived from diatoms, because these organisms are, as a rule, 

 apparantly brown rather than green/ This objection I find 

 to bo based upon a misapprehension of the structure of the 

 Diatomacea-, as may be gathered from the following general 

 statement taken from Sachs' "Text. Book of Botany," one of 

 the latest and highest authorities. On page 223 he says: 



"The diatoms are the only algae except the Conjugates in 

 which the chlorophyll occurs in the form of discs and bands, 

 but in some forms it is also found in grains, and the green 

 coloring matter is concealed like the chlorophyll grains in 

 Fucacca, by a buff-colored substance diatomine orphycox- 

 authine." It appears then, according to the foregoing quota- 

 tion, that it is not impossible for diatoms to be the cause of 

 the. green tint in oysters, which let me remark is very nearlv 

 that of some pale green forms of those organisms which 1 

 have observed in water from oyster coves where I have con- 

 ducted microscopic studies. Besides, sections through the in- 

 testine of the oyster frequently reveal the fact that diatoms 

 must have constituted a very large proportion of 'the food of 

 the animal, judging from the profusion of the empty frustules 

 of these minute plants, which are very often found together 

 with the indigestible, earthy and silicious particles with which 

 the alimentary canal is packed. 



I find the liver to be normally of a brownish red color in both 

 the American and European oyster, sometimes verging toward 

 green. When the flesh or gills of the animal is green, the 

 liver almost invariably partakes of this color, but in an inten- 

 sified degree. The green stain or tincture appears in some 

 cases to have affected the internal ends of the cells which line 

 the follicles or ultimate saccules of the liver. This color is able 

 to survive prolonged immersion in chromic acid and alcohol, 

 and does not allow carmine to replace it in sections which 

 have been stained with an ammoniaeal solution of that color, 

 the effect of which is to produce a result similar to double 

 staining in green and red. The singular green elements scat- 

 tered through the connective tissue remain equally well 

 defined, and do not take the carmine dye. I at first believed 

 these to be parasitic vegetable organisms, and I also supposed 

 I saw starch granules in thern, which physical tests with an 

 iodine solution failed to confirm. These large and small green 

 granular bodies in the connective tissue, and those close to the 

 intestinal wall, as well as those in the heart, I find present in 

 fewer numbers in white-fleshed oysters, but simply with this 

 difference, that they are devoid of the green color. It is evi- 

 dent, therefore, that they cannot be of the nature of para- 

 sites, though the color is limited to them, only the surround- 

 ing tissue, except in the region of the heart, appearing of the 

 normal tint. This condition of the specimens observed by me 

 does not, however, disprove the possibility of the occurrence 

 of vegetable parasites iu the oyster, where there is as much, 

 or perhaps more, likelihood of their occurring than in some 

 much more highly-organized animals. 



It is a fact, however, that the oyster is singularly free frpm 

 true parasites of all kinds; the oyster crab being perhaps 

 the only creature which is ever frequently found within its 

 valves, and then only as a harmless messmate- More 

 recently it has been my good fortune to be able to study a 

 second lot of European oysters, in two varieties of which the 

 green color was unusually developed, especially in the heart. 

 In a specimen of Falmouth oyster I found a l»rge cyst or sack 

 in the mantle near the edge filled with green cells whieh like 

 those in the heart when opened readily separated from one 

 another, being quite as independent of "e*ch other as the ordi- 

 nary discoidal corpuscles in the eervm of red blood. The 

 hearts of affected specimens were found to have the wall of 

 the ventricle abnormally thick, ana covered inside with the 

 readily detachable green cells in a thick layer and measuring 

 1- 2000th of an inch in diameter. An application of the crucial 

 test for starch with iodine gave a negative result. When 

 iodine was first applied to taese cells in strong solution and 

 then treated with sulphuric, acid with the result that the 

 characteristic blue reaction was not developed, showed that 

 there was no cellulose wall covering them, and that they were 

 most, positively not parasitic, algous vegetable organisms. In 

 potassic hydrate solution they underwent complete solution, a 

 further proof of She absence of cellulose. 



Their dimeuoions, 1-2000 of an inch, is the same as that of 

 the blood eel! of the oyster. They are nucleated, with the 

 nucleus in an eccentric position as in the blood-cell of the ani- 

 mal. Th-ir occurrence in the heart and gills so as to tinge 

 those i/rgans of their own color is almost positive proof of 

 their due origin and character. Furthermore, I find in sec- 

 tions that they sometimes occlude the blood-channels. In the 

 erst in the mantles, as in the heart, they are free, and in the. 

 normal untinged heart, they are not abundant. All of the 

 foregoing facts indicate that these green bodies are in reality 

 blood-cells which belong to the animal. How they become 

 green is not easy to determine. The fact remains that no 

 evidence of the presence of green Micrococci, or Microbia as 

 independent existences could be made out. The fact that I 

 foimd instances in green oysters where an unusual greenish 

 material was found in the f ollicles of liver, the living cells of 

 which were also affected, would indicate that the color was 

 probably absorbed from the food of the animal, which, as we 

 know, consists largely of living vegetable matter. It is not 

 iinpi obable that the tinged nutritive juices transuded through 

 the walls of the alimentary canal, acquired the color of the 

 food whieh had been dissolved by the digestive juices. 



How to account for the accumulation of the green cells in 

 the heart and in cysts in the mantle is not, however, an easy 

 matter, unless one" be permitted to suppose that the acquisi- 

 tion of the green color by the blood cells is in reality a more 

 or less decidedly diseased condition, for which we have no 

 ground in fact, since the green oysters are in apparently as 

 good health as the white ones. They are found "fat fl or 

 "poor," just as it may have happened that their food was 

 abundant or the reverse. They are also found in all stages of 

 the ''greened" condition. Sometimes they have only a very 

 faint tinge of the gills, or they may bo so deeply tinged as to 

 appear unpalatable, with the heart of a deep green, or with 

 green cysts developed in the mantle or with clouds of this 

 color shading the latter organ in certain places. A vastly 

 greater proportion of green oysters are eaten in this country, 

 at all events, than is generally supposed, especially of those 

 just faintly tinged in the gills. 



If it be objected that, the green color indicates an unhealth- 

 f ul condition of the animal, it may be stated that other color 

 variations of the flesh have fallen under my observation re- 

 cently. What is now alluded to is the yellowish, verging 

 toward a reddish cast, which is sometimes noticed in the 

 gills and mantle of both the American and European species. 

 This, in all probability, like the green color, is due to the 

 reddish-brown matter which is contained in much of the di- 

 atomaeeous food of the animal. 



Mr. J. M. Carley has also called ray attention to these vari- 

 ations and was inclined to attribute them to the soil in the 

 vicinity of the beds. But if the classical writers are to be 

 trusted, to the green, yellow and white-fleshed sorts we must 

 add red, tawny "and bjack-fleshed ones. Pliny tells us of red 

 oysters found in Spain, of others of a tawny hue in Hlyricum, 

 and of black ones at Circeii, the latter being, he says, black 

 both in meat and shell. Horace and other writers awarded 

 these the palm of excellence. However, the black appear- 

 ance may only have been due to an abundance of the natural 

 purple pigment in the mantles of the animal, which varies 

 very much in different forms; some, judging from the dark 

 purple color of the whole inside of the shell, must have the 

 whole of the mantle of the same tint. The amount of color 

 in the mantle, especially at its border, varies in local vari- 

 eties of both the American and European species, as may 

 often be noticed. 



The most important glandular appendage of the alimentary 

 tract of the oyster is the liver, It communicates by means of 

 a number of wide ducts with a very irregularly formed 

 cavity, which we may designate as the stomach proper, in 

 which the food of the animal comes into contact with the 

 digestive juices poured out by the ultimate follicles of the 

 liver, to undergo solution preparatory to its absorption during 

 its passage through the singularly formed intestine. 



It thin shoes of the animal are examined "under the micro- 



scope we find the walls of the stomach continuous with the 

 walls of the great ducts of the liver. These great ducts divide 

 and sub-divide until they break up into a great number of 

 blind ovoidal sacks, into which the biliary secretion is poured 

 from tho cells of their walls. A thick stratum of these fol- 

 licles surrounds the stomach, except at its back or dorsal side. 

 It is not correct to speak of the liver of the oyster as we speak 

 of the liver of a higher animal. Its function in tho oyster is 

 the same as that of three different glands in us, viz., the gas- 

 tric follicles, the pancreas and liver, to which we may add the 

 salivary, making a total of four in the higher animals which 

 is represented by a single organ in the oyster. In fact, experi- 

 ment has shown that the secretion of the liver of mollusks 

 combines characters of at least two if not three of the gland- ' 

 ular appendages of the intestine of vertebrated animals. 

 There are absolutely no triturating organs in the oyster for the 

 comminution of its food; it is simply "macerated in tho gland-' 

 ular secretion of the liver and swept along through the intes- 

 tine by the combined vibratory action of innumerable fine 

 filaments with winch the walls of the stomach, hepatic duot» 

 and intestine are clothed. 



In this way the nutritive matters of the food are acte/ upon , 

 in two ways; first, a peculiar organic ferment deri"^ from 

 the liver reduces them to a condition in which t^ey may be 

 absorbed ; secondly, in order that the latter process may b£ 

 favored it is propelled through an in testing canal which is 

 peculiarly constructed so as to present a$5""g e an amount of 

 absorbent surface as possible. This »b accomplished by a 

 double induplication or fold which extends for the whole 

 length of the intestine, the cavit<-of which, in consequence, 

 appears almost crescent-shaped when cut straight across. On 

 the concave side the intestine wall is thrown into numerous 

 very narrow longitudinal colds, which further serve to in- 

 crease the absorbing surface. Such minor folds are also 

 noticed in the stomach, and some of these may even have a 

 special glandular function. There are no muscular fibres in 

 tne wall" of the intestine as in vertebrates, and the sole motive 

 force which propels the indigestible as well as digestible por- 

 tions of the f-»od through the alimentary canal is exerted by 

 the innumerable vibratory cilia with which its inner surface 

 is clothe"' The intestinal wall is wholly made up of columnar 

 cells -which are in direct contact externally with the con- 

 nective tissue which is traversed by numerous large and small 

 bl<>od-vessels devoid of specialized walls. 



This apparatus is admirably suited to render the microscopic 

 life found in the vicinity of the animal available as a food 

 supply. The vortices created by the innumerable vibratory 

 filaments which cover the mantle, gills and palps of the oyster, 

 enables it to draw its food toward itself and at the same time 

 the microscopic host is hurled into the capacious throat of the 

 animal to undergo conversion into its substance as described 

 above. The mode in which the tissues may become tinged 

 by the consumption of green spores, diatomes or desmids, it is 

 easy to infer from the foregoing description of the digestive 

 apparatus of the animal; and the colorless blood-cells, moving 

 in a thin, watery liquor sanguinis, would, judging from their 

 amcebif orm character, readily absorb any tinge acquired by 

 the latter from the intestinal juices. 



I have already discussed in a desultory way the microscopic. 

 marine fauna of certain districts on the Chesapeake Bay, 

 where I have been engaged upon the study of the oyster 

 under the auspices of the Maryland Commission, but what I 

 have done has been simply preliminary and necessarily in- 

 complete. Before we are ready to deal with the material on 

 which the oyster feeds, we desire a more perfect acquaintance 

 with the microscopic life which grows upon oyster beds and 

 swims about in the adjacent waters. From the fact that the 

 lower forms of life in fresh water often appear in great abun- 

 dance one year, while in the next, from some unexplained 

 cause, none of the same species will be found in the same 

 situation, we may conclude that similar seasonal variations 

 occur in the phases of tho miroscopic life of a given oyster 

 bed and its vicinity. 



Such yearly variations in the abundance of microscopic life 

 are probably the causes of the variable condition of the 

 oysters taken from the same beds during the same Beason of 

 different years. Violent or sudden changes of temperature 

 are probably often the cause of the destruction of a great 

 amount of the minute life upon which the oyster feeds. Back- 

 ward and storcny seasons doubtless also affect thj abundance 

 of the microscopic life of the sea. All of these questions 

 have, however, as yet been scarcely touched, and, judging 

 from the disposition of many of our students of zoology to be 

 content merely with a description of new species and the 

 compilation of "lists, instead of also entering into investigations 

 of the life-histories, the relative abundance of individuals, 

 and the influence of surrounding conditions upon the forms 

 they study, it will take some time yet before we get the infor- 

 mation so much desired. When we arrive at this knowledge 

 we will know why it is that oysters taken from a certain bed 

 are in good condition for a season or two and then for one or 

 more years are found to be watery and of poor qualitv, as 

 well as why it is that the oysters of certain beds, which for 

 years have "had a high reputation for their fine qualities, are 

 suddenly found to be more or less green in the beard, as I have 

 betn informed is now the case with the oysters of Lynn Haven 

 Baj r , Virginia. 



Speaking of the abundance of the Na.vicula ostrearia of 

 Kiitzing, M. Benjamin Gaillon, in 1S20, said that they inhabit 

 the water of the tanks o : ' parks" in which the oysters as e 

 grown in such immeuse abundance, at certain seasons of the 

 year, that they can only be compared to the grains of dust 

 which rise in clouds and obscure the air in dusty weather. 

 Dr. Johnston, speaking of the French oysters, says that in 

 order to communicate to them a green color, which, as with 

 us (in England), enhances their value in tho market and in the 

 estimation of the epicure, they are placed for a time in tanks 

 or " parks," formed in particular places near high-water 

 mark, and into which the sea can bo admitted at pleasure by 

 means of sluices; the. water being kept shallow and left at 

 rest is favorable to the growth of the green Conferral and 

 Vivas; and with these there ore generated at the same time 

 innumerable crustaceous animalcules which serve the oysters 

 for food, and tincture then flesh with the desirable, hue. 



At any rate, without criticising the allusions to tie 

 crustacean food of the oyster, these observations give us some 

 hints regarding the advantages arising from the cultivation 

 of oysters in more or less stagnant water, in which, as in the 

 French parks or claires, an abundance of microscopic life 

 would be generated in consequence of a nearly uniform 

 temperature, higher in the early autumn months at least 

 than the waters of the open sea, where cold currents also 

 would tend to make it still less uniform and thus interfere 

 with the generation of the minute food of the oyster. In 

 other words, it would appear that the effect of the French 

 method is to furnish the best conditions for the rapid and 

 constant propagation of an immense, amount of microscopic 

 food well adapted to nourish the oyster. That unlike oysters 

 exposed to a rapid flow of water on a bottom barren of life, 

 they grow and quickly come into a saleable condition. 



In this country narrow coves and inlets with comparatively 

 shallow water appear to furnish the best conditions for the 

 nutrition and growth of oysters; and according to my own 

 experience these are the places where w r e actually find minute 

 animal and vegetable life in the greatest abundance, and, as 

 might have been expected, the oysters planted in such situa- 

 tions appear to be in good condition early in tho autumn, 

 long betore those whieh are found in deeper and more active 

 water, where their food has less chance to multiply. If the 

 French mode applies successfully to an inferior species, ours, 

 which grows so much more rapidly, ought to derive a pro- 

 portionally greater benefit from being treated in the same 

 manner. 



As to the influence of brackish water in improving the con- 



