Sept. II, 1879] 



NATURE 



465 



the currents of the water, caused by waves, wind, or tides, and 

 doubtless in many cases through the incessant movements of 

 some marine animals. The greater the distance between the 

 antheridia and the carpogonia, the smaller are, of course, the 

 chances of fertilisation ; the more violently the water is moved 

 about in the vicinity of and between the separated organs, the 

 more probably will the lucky accident of the union of both 

 elements take place. 



During a long series of investigations of the reproductive phe- 

 nomena of Polysiphonia, Dr. Dodel-Port found regularly on the 

 bushy thallus, and particularly upon the uppermost and youngest 

 branches, an enormous numbe» of the well-known stalked ani- 

 malcules, VorticellEe, which had settled there, and were, as usual, 

 in incessant motion. Often they appeared in dozens in the field 

 of the microscope, and, with the constant vibration of their cilia, 

 they were very troublesome, at least up to the moment when Dr. 

 Dodel-Port had directly observed their friendly cooperation in 

 the fertilisation he was studying. He was a frequent witness of 

 the process depicted in Fig. 3, where numerous antherozoids were 

 whirled round and round in the whirl caused by a Vorticella, and 

 where frequently antherozoids came into contact with the tricho- 

 gyne, and remained attached to it (Fig. 3, / and /') for a longer 

 or shorter period. It was entirely due to the motion caused by 

 Vorticellse that Dr. Dodel-Port was enabled to follow the phe- 

 nomenon of the attachment of the antherozoids to the trichogyne 

 from begiiming to end. The motions of the Vorticellse are 

 particularly varied through the repeated contractions of their 

 stalks into short spirals, and thus they cause various currents in 

 the water, by all of which the antherozoids are carried along like 

 any other small passive body that may be suspended in the water. 

 (Compare Fig. 2, where one of the Vorticellse is just contracting 

 its stalk, the arrows in each case indicating the direction of the 

 currents.) 



The presence of numerous Vorticellse thus imparts to the 

 passive antherozoids a kind of motion much resembling that 

 of the sperm-cells of other cryptogams which are endowed with 

 active cilia. From this follows, with mathematical certainty, 

 that the probability of the antherozoid falling on the trichogyne 

 in the presence of Vorticella; is immensely greater than that 

 which would exist were there no animals present. 



At the same time, it is evident that this probability is yet in- 

 creased in the case of Polysiphonia subulata through the presence 

 of the forked hair, g h, in the vicinity of the trichogyne, because 

 the whirls caused by the animalcules will often be cleft by the 

 forked hair, and thus secondary whirls will be produced. Often 

 in Polysiphonia, carpogonia were found which were not fertilised. 

 Thus Fig. 4 represents a ripe and spore- ejecting cystocarp, cy, 

 and two carpogonia, uc^, which remained unfertilised. This 

 was particularly the case on thallus-branches, which were less 

 densely crowded with Vorticelloe — another, although negative, 

 proof of Dr. DodelPort's theory. It is not particnlarly remark- 

 able that Vorticella should inhabit Polysiphonia in large numbers, 

 because these animalcules, as Dr. Dodel-Port observed, feed 

 with predilection on the antherozoids of this plant. Thus we 

 have here a condition of things similar to the relations between 

 certain flowers and pollen-consuming insects. The consumption 

 of antherozoids by the Vorticella; is, of course, far too insignifi- 

 cant to merit any consideration, particularly if compared to the 

 great advantages regarding fertilisation which the presence of 

 the animalcules brings with it. Moreover, a comparison of the 

 male plant of Polysiphonia with a female specimen shows that 

 here also, as in most phanerogams, thousands more male cells 

 are formed than are necessary for fertilisation. 



After fertilisation the carpogonium develops into a cystocarp, 

 i.e., the spore-forming fruit (Fig. 4). Shortly after fertilisation 

 the whole hair apparatus disappears. The wall-cells of the car- 

 pogonium now begin to grow quickly and to divide by mem- 

 branes perpendicular to the surface. They form a cellular case 

 (/< /(, Fig. 4), which has an orifice in the apex, long before the 

 spores are ripe. In the meantime the central cell of the fer- 

 tilised carpogonium begins to form a number of densely-packed 

 short branches, which, as a series of cells radiating in all direc- 

 tions, fill the basis of the capsule-shaped fruit. The central 

 cell is therefore called the placenta-cell. At the ends of the 

 ramified cell-series which radiate from it, pear-shaped and dark 

 red spores form (carpospores), which, as soon as tliey have 

 attained a certain size, become detached and pass into the water 

 through the orifice at the apex of the cystocarp. In this state 

 they are perfectly capable of further development and soon 

 begin to germinate. 



Dr. Dodel-Port concludes his interesting treatise with the 

 following suggestive sentences : — 



" The total absence of active organs of locomotion in the 

 antherozoids of Florid ese points to a common ancestor from 

 which the different branches of the Floridea; have inherited the 

 immobility of the antherozoids. No doubt that during the dif- 

 ferentiation of the red seaweeds many forms have died out in 

 consequence of the fertilisation not taking place through the 

 passivity of the male cells, while other forms have retired to 

 localities which through active water-currents favour the process 

 of fertilisation in spite of the immobility of the antherozoids. 

 It is well known that now we find most of the present species of 

 Floridese on the coasts of warmer seas, which are constantly 

 washed by the waves, while the northern coasts, which are 

 covered by crusts of ice during a great portion of the year, are 

 very poor in red seaweeds. Future researches will have to show 

 how far in many of these aquatic plants the differentiation of 

 the genera took place in the sense of an adaptation to the small 

 marine animals which inhabit them and favour their fertilisation in 

 the way I have pointed out. If many seaweeds in their bushy shrub- 

 like thallus harbour certain infusoria, bryozoa, hydrie, sponges, 

 Crustacea, annelids, and small starfishes, and offer to them excellent 

 hiding-places or nourishment, so that these animals inhabit them 

 with special predilection, then it is certainly possible that occa- 

 sionally a correlation was formed or adaptation took place, which 

 was mutually advantageous and which would find numerous 

 analogies in the domain of the multiple cross relations between 

 the higher flowering plants and insects. In this sense I consider 

 it my duty to submit to the criticism of biologists a point hitherto 

 overlooked in the biology of red seaweeds, and bearing upon 

 the explanation of the morphological differentiation of submerged 

 aquatic plants," 



THE BRITISH ASSOCIATION 

 REPORTS 



Report of the Committee appointed for the Purpose oj Arranging 

 forthe Occupation of a Table at the Zoological Station at Naples, the 

 Committee consistins; of Dr. M. Foster, Prof. Rolleston, Mr. Dew- 

 Smith (Secretary), Prof. Huxley, Dr. Carpenter, Dr. Gwyn Jeffreys, 

 Mr. Sclater, Mr. F. M. Balfour, Sir C. Wyville Thomson, and 

 Prof. Ray Lankester. — Since we submitted ovir last Report to the 

 Association, the Zoological Station at Naples has continued to 

 be successful in providing opportunity and appliances for 

 naturalists studying the various forms of marine animals and 

 plants. From September i, 1878, to the end of July, 1879, 

 twenty-six naturalists have occupied the tables at the Institution. 

 A list of their names and the time of stay will be found appended. 

 During the same period, packages of specimens have been 

 forwarded to fifty-one different naturalists and institutions. A 

 list of these is also appended. 



Recently a new department has been added to the station. 

 Through this naturalists will be enabled to obtain mounted 

 specimens of microscopic animals, viz., sections of embryos of 

 all kinds of fishes, &c., preparations of larva; or other animals 

 too small for being sent in alcohol or other preservative solutions. 

 Next year a catalogue of these specimens will be published, and 

 the station will be prepared to send the specimens to any naturalist 

 requiring them. 



Trials of diving by means of the new Scaphander apparatus 

 have also recently been made with very satisfactory results. 



The aquarium of the station is being in part reconstructed, 

 with some important new features, viz., moveable rockwork, for 

 saving and examining the different aniinals which thrive by them- 

 selves on these rocks. This will enable statistical notes to be 

 established on the growth of these animals, and on such changes 

 as may occur by changing their habitat, inasmuch as these rocks 

 may be replaced in the sea at different depths. 



The following monographs are in preparation by workers in 

 the station :— Ctenophorte, Fierafer, Balanoglossus, Sipunculoidos, 

 Capitellida;, PlanariDe, NemertineK, Pycnogonida;, Caprdlida:, 

 and on several families of Alga;. 



Three parts of the " Mittheilungen aus der zoologischen bta- 

 tion zu Neapel, zugleich ein Rcpertorium fiir Mittelmeerkunde 

 have been puljlished, containing sixteen papers illustrated with 

 many very carefully executed plates. Further parts are m acUve 

 preparation. , „ . 1 



It is, moreover, intended to publish the foUowuig works :— 



"Fauna und Flora dcs Golfes von Neapel und der angren- 



