Oct. ii, 1883] 



NA TURE 



58r 



if blown by the wind, simply alights on the surface of the seed 

 and fertilises it directly. In plants with covered seeds, on the 

 other hand, the pollen cannot gain direct access to the ovules, 

 but can only fall on the surface of the envelope formed by thecar- 

 pellary leaves. This covering has to be penetrated before fer- 

 tili-ation of the seeds can be effected. For this purpose several 

 adaptations of tissues, modifications of structures, and changes 

 in the position of the ovules are rendered necessary, all of which 

 might easily be dispensed with were the seeds exposed as they 

 are in Gymnosperms. It can hardly be supposed that all this 

 specialisation, whereby the process of fertilisation so simply 

 performed in Gymnosperms becomes complicated by being 

 broken up into numerous subsidiary process ;s, should be called 

 into play unless some very important end were to be attained by 

 the presence of a completely closed pistil. What then is the/v/< 

 of the pistil ? The young seeds are the most vital parts of the 

 vegetable organism. Composed of delicate cells, containing 

 much nitrogen and phosphorus, they may be said to constitute 

 the chemical and physiological wealth of the plant. On this 

 account they must be carefully guarded from any external influ- 

 ence that would degrade their chemical constitution or lead to a 

 misappropriation of the nutritious matters they contain. Now 

 it is well known that the leaves and stems of nearly all plants 

 are subject to the attacks of parasitic fungi. The spores of 

 these parasites germinate on the leaves of the plant on which 

 they alight, and appropriate its juices to their own use, as, for 

 example, in the case of the fungus which occasions the potato 

 disease. All kinds of moulds, putrefaction, and fermentation 

 are in like manner produced by the development of spores 

 falling frsm the atmosphere which have found a favourable soil 

 for their growth. Now a more suitable pabulum or nidus for 

 the growth of mould germs can hardly be imagined than that 

 which would be afforded by the immature ovules, seeing that 

 in them is collected a large amount of easily assimilable 

 matter destined for the nutrition of the embryonic plant. 

 There can be little doubt then that the disadvantages which 

 the pistil brings with it, and the higher organisation thereby 

 entailed, are more than compensated for by the security 

 which it gives against the entrance of fungus spores. The 

 pea pod is in fact the counterpart of the hermetically sealed 

 or stoppered flasks, in which Tyndal and Pasteur performed 

 their well known experiments on the preservation of organic 

 fluids against putrefactive changes. These observers found that 

 it was possible to preserve beef tea or other organic infusion 

 for any length of time, provided no air was admitted to the 

 flask, or if care were taken to filter the air from all organic 

 germs by passing it through cotton wool, &c, before allowing 

 it to have access to the infusion. The pistil of a flower then 

 may be regarded as analogous to the flask in these experiments. 

 The loose cellular substance of the style, and the acid secretion 

 on the stigma, may in like manner serve to filter the air before 

 it reaches the ovules contained within the ovary. At any rate 

 the air must pass through the substance of the carpels before it 

 can reach the ovules. 1 When this fact is viewed in connection 

 with the experiments of Van Tieghem, which show how difficult 

 it is to effect the direct fertilisation of ovules with pollen, owing 

 to the constant appearance of microscopic fungi, a new light is 

 thrown on a vast number of vegetable and animal structures. 

 The same principle operates not only among phanerogams, but 

 even among the cryptogams ; nor could a principle of such 

 general application in the vegetable world have failed to play 

 an important part in the animal kingdom. It is remarkable 

 then to find that within the cup of the commonest wild flower 

 we have the results of recent scientific research anticipated, the 

 benefits of the antiseptic system as completely secured as by 

 modern surgery, and a parallel between nature and art which 

 agrees even to the minutest detail. 



Protoplasmic Continuity in the Florida?, by Thomas Mick, 

 B.A., li.Sc. — The author has made an extensive series of 

 observations on a large number of species belonging to the more 

 important genera of Floridese, with special reference to the 

 question of protoplasmic continuity. lie finds in all the 

 es examined that there is such a continuity, and that 

 of the clearest and most definite character. In the simpler 

 filamentous types, such as Pdrocclis crucnta and Calli- 

 thamnion Remit, the protoplasm of each cell is united 

 with the protoplasm of contiguous eel's by means of a 



1 This view of the function of the carj e!s is corroborated by the fact » b- 

 served in the case of Reseda, the carpels of which open soon after fertilisa- 

 tion. After dry weather an accumulation of sand and dust frequently takes 

 place within the ovary of Reseda. 



fine protoplasmic thread. This obtains throughout the whole 

 plant. In the more complex types, such as Callithamnion 

 roseum, C. arbuscula, and C. tetragonum, the arrangements for 

 continuity are of a more elaborate character. The contents of 

 the axial cells are not only united with one another, but also 

 with those of the cortical cells, however numerous these may be. 

 The cortical cells also display continuity inter se. Ptilo.'a elegans 

 is a most instructive form, as here the connective threads may be 

 easily traced from the tips of the ultimate branchlets to the base 

 of the stipes of the frond. As the threads become older, they 

 increase in thickness, thus showing that they are not merely 

 temporary or effete structures. On the stouter connecting cuds 

 as it of ring or collar is developed at about the middle point, and 

 over this is stretched, in some eases, a delicate diaphragm. The 

 behaviour of both ring and diaphragm when treated with micro- 

 chemical reagents, is similar to that of the ordinary protoplasm. 



On Peripatus, by Adam Sedgwick. — Mr. Sedgwick showed 

 living specimens of this animal, and briefly described them. 



Some newly-discovered Localities of the Rare Slug Testacella 

 halloloiJea, by E. J. Lowe, F. R.S. — This rare and hitherto ex- 

 tremely local nest-eating slug has recently been found in various 

 places in Monmouthshire and South Wales. Shirecester Hall, 

 Sh'renewton Village, Tatton Court, Hardwick, Chepstow, 

 Cardiff, and various other places, were mentioned as producing 

 more or less abundant quantities of this interesting creature. 



Department of Anatomy and Physiology 



On the Relations of Protoplasm and Cell-wall in the Vegetable 



Cell, by F. O. Bower. — After tracing the history of this subject, 

 it was concluded that it has now been demonstrated with as 

 much certainty as is possible by the use of microchemical and 

 staining reagents, that in certain cases, the number of which is 

 now constantly being increased, there is a direct connection 

 between the protoplasmic bodies on opposite sides of cell-walls, 

 and that this connection is established by means of fine strings of 

 protoplasm which, in the cases observed, run nearly trans- 

 versely through the walls. The question remains whether this is 

 the only mode of permeation of the cell-wall by protoplasm. 

 The author could not accept it as proved as yet that any further 

 permeation of the cell-wall by protoplasm, as a reticulum or 

 otherwise, really exists, but he brought forward certain grounds 

 for regarding such a oermeation as possible or even probable, 

 taking into account chiefly those phenomena observed in free cell- 

 walls, in order thereby to avoid any confusion with connecting 

 strings, such as those already proved to exist: — 1. The strings 

 already observed vary greatly in thickness, from the well marked 

 to the indistinguishable ; thus we have evidence of the existence 

 of strings which would probably not have been recognised were it 

 not for comparison with other examples. Further, it has been 

 shown, in the author's paper on plasmolysis, that protoplasm 

 may be drawn out into strings so fine as to defy definition even 

 by high powers of the microscope ; thus there can be no objection 

 on. the ground of the small size of the hypothetical strings or 

 reticulum. 2. Those cases in which a perforation of cell-walls 

 has been demonstrated are those very cases in which a most 

 efficient physiological connection is required. There is no 

 reason why a less obvious permeation should be denied where 

 the requirements are less, but by no means absent. 3. There is 

 a priori probability of some form of permeation of cell-wall by 

 protoplasm if Strasburger's account of the growth of cell-walls 

 be correct. 4. A strong argument in favour of such general 

 permeation of walls by protoplasm is found in the existence of 

 important chemical changes in the substance of cettain cell-walls 

 at points at a considerable distance from the main protoplasmic 

 body, e.g. formation of cuticular substance, wax, &c. , which 

 differ fundamentally from cellulose, are insoluble in water, and 

 are apparently formed in the wall itself. The tendency of recent 

 observations is to show more and more clearly how clo?e the con- 

 nection of protoplasm with the important chemical changes in 

 the plant is ; thus it appears probable that protoplasm is present 

 in some form or other in the cell-wall. Reasons were also given 

 for thinking that the exposure to air is not an important factor 

 in the above changes. These and other considerations show that 

 though this permeation of the wall cannot be accepted as proved 

 as yet in any one case, still the subject deserves more close 

 attention than it has yet received, while it may be expected 

 that the application of new methods may produce definite results 

 bearing on this very important question. 



On the Occurrence of Chlorophyll in Animals, by C. A. 

 MacMunn, M.D., F.C.S. — The difficulties attending the recog- 



