September i, 1898] 



NA TURE 



425 



He then delivered the presidential address, which was printed 

 in extenso in our last week's issue. 



Profs. Milne-Edwards, Jentink, Collett, Haeckel, von Graff, 

 Hertwig, Marsh, Mitsukuri, Salensky and Vaillant were elected 

 Vice-Presidents ; and Dr. Hoek, Dr. Gadow, Dr. Plate and 

 M. Janet were elected Secretaries of the Sections. The meeting 

 then proceeded to receive the reports of committees appointed 

 at the third Congress to consider various matters of zoological 

 importance. The committee on zoological nomenclature, 

 having been unable to come to a unanimous decision, applied 

 for power to add to their number, which was granted. The 

 question of zoological nomenclature was, therefore, not discussed 

 at the Congress, but was referred back for consideration by the 

 augmented committee. Dr. P. Hoek announced, on behalf of 

 another committee, that favourable arrangements were about to be 

 made with the international postal authorities for the transmission 

 of animals and plants not intended as merchandise. 



In the afternoon, in Section A, Mr. Stanley Gardiner read a 

 paper on the '"Building of Atolls," suggesting that the depths 

 at which corals and nullipores live is determined by the depth 

 to which light can penetrate sea-water, the food of corals being 

 derived entirely from the commensal algre. The form of the 

 atoll-reef was shown lo be due to the continuous addition of 

 marginal Ixittresses and the dissolution of the central parts. In 

 this, and in other respects, the author supports the theory of 

 atoll-formation propounded by Sir John Murray. Prof. 

 Mitsukuri, discoursing on " Zoological matters in Japan," 

 pointed out that the transition from comparative barbarism to 

 the present degree of scientific culture has not been as sudden 

 as is generally supposed. He quoted some scientific works 

 published in Japan in the ninth century, and called attention to 

 the foundation of the Botanical Gardens of the University of 

 Tokyo in i68l. He gave an account of the zoological labor- 

 atories at Tokyo, and of the marine station which has recently 

 been erected near that town. Prof. Salensky read a paper on 

 " Heteroblasty," by which name he designates the origin from 

 different embryonic sources of organs, similar in position and 

 function, in nearly related animals. He adduced as examples 

 the development of the alimentary tract from the ectoderm in 

 insects ; the development of the peribranchial cavities in buds 

 and embryos of Ascidians, and the development of the heart in 

 Ascidians and Vertebrates. 



In Section B, Prof. Milne-Edwards read a paper on the 

 *• Extinct Animals of Madagascar," in which he referred to the 

 valuable collections made by M. Grandidier and Dr. Forsyth- 

 Major. He compared the Aipyornis wiih the Dinornis of New 

 Zealand, and drew a ])arallel between the extinct fauna of 

 Madagascar and that of tlie Australasian area. 



Prof. O. C. Marsh made a communication on the "Value 

 of Type Specimens and the Importance of their Preservation," 

 dealing more especially with the extinct Vertebrata. He 

 pointed out that the value of type specimens depends on. the 

 maturity of the animal and the state of preservation and com- 

 pleteness of the parts. Type specimens must show character- 

 istic features. The association of fragments to supplement an 

 incomplete type is a practice fraught with great danger of con- 

 fusion to subsequent investigators. Prof. Marsh advocated 

 depositing types in large endowed museums as affording better 

 chances of safe preservation than local museums ; and he 

 regarded it as a wise regulation that type specimens should not 

 be permitted to leave the museum in which they are deposited. 



Dr. Van Bemmelen showed that in Ornithorhynchus the 

 temporal arch has two roots instead of one, a fact which sug- 

 gests forcibly the articulation of the mandible with a persistent 

 quadrate, as in reptiles. Prof. Seeley pointed out that the dis- 

 covery had previously been made by himself. 



Mr. Graham Kerr described the habits and development of 

 Lepidosirev, and exhibited a splendid collection of specimens 

 which he collected during his recent stay in Paraguay. 



In Section C, Prof. Plate gave an account of the " Com- 

 parative Anatomy of the Chitons," showing that in these 

 molluscs, generally believed to be the most primitive of existing 

 Gastropods, there is a far greater diversity of internal organis- 

 ation than might be suspected from their uniform appearance. 

 Prof. Plate also described a newly discovered Protozoan which 

 lives as a parasite in the mantle cavity of Chiton. Mr. E. S. 

 Goodrich demonstrated the structure of the complex nephridial 

 organs which occur in the Polychaete worm Glycera. Mr. C. F. 

 Rousselet described a new method of preserving Rotifers in the 

 ext-ended condition, by narcotising them by the slow addition of 



NO. 1505, VOL. 58] 



a weak solution of cocain, and then killing them by a weak solu- 

 tion of osmic acid. The specimens are best mounted in 

 formol. Some excellent specimens prepared in this way were 

 exhibited. 



In a paper read in Section D, on " Some points in the clas- 

 sification of Insects," Dr. David Sharp pointed out that in some 

 insects the wings are developed outside the body, while in the 

 others they do not appear at all, or are developed inside the 

 body and are subsequently everted ; and he claimed that in a 

 classificatory scheme the perfection or imperfection of the 

 metamorphosis should be subordinated to this feature. He 

 proposed, therefore, to divide the insects into four groups, the 

 Apterygota, quite wingless and in all probability descended 

 from wingless ancestors, the Anapterygota, which, though wing- 

 less and parasitic, exhibit an acquired anietabolism as regards 

 the wings, the Exofterygota, in which the wings are developed 

 outside the body, and the Endop'.erygota, comprising the vast 

 majority of existing hexapod insects, in which the wings de- 

 velop inside the body. With regard to the geological antiquity 

 of the groups, there is evidence to show that the exopterygotous 

 insects are the most primitive, they only extending as far back 

 as the Palreozoic. 



Mr. M. C. Piepers summarised the results of his observations 

 on the colours of insects in a paper entitled "Evolution of 

 Colour in Lepidoptera," in which he concludes that there has 

 taken place, and is still in progress, a process of colour-change 

 affecting not only the metamorphosis of a given species, but also 

 the evolution of the species and genera of a family. He would 

 explain colour-polymorphism as a phenomenon of arrestation of 

 this continuous evolution at varying stages, and sexual colour- 

 differences as due to unequal advances by the two sexes in the 

 same direction. The existing Pieridoe are, according to this 

 view, evolved from a reddish ancestor. With advancing 

 evolution the colour has become paler ; first orange, then 

 yellow, and in the most highly evolved species a pure white. 

 Albino specimens of a species normally yellow are to be 

 regarded as sports which have advanced further in this evolu- 

 tionary scale than the majority. The progression of colour- 

 change is not, however, the same in all families of Lepidoptera. 

 In some, for instance, the primitive colour is red, and the 

 successive stages are gradually darker, culminating in black. 



A communication was also read from M. Bordage, giving the 

 results of experiments made by him to determine the relation of 

 the colour of the chrysalids of certain species of Lepidoptera to 

 the colour of their environment. The chrysalids of Papilio 

 demo/ens and /'. disparalis appeared to be completely in- 

 sensitive to the colour of their surroundings ; but the experi- 

 menter has witnessed distinct, though feeble, efforts to respond 

 on the part of Atella phalanta, Eiip'oea goudotii, and Danais 

 chrysippHs. The intensity of the light and the brightness or 

 dulness of the surroundings appear to be more important factors 

 than the actual colour of the latter. The age of the chrysalis 

 also materially affects the result. 



On Wednesday morning a general meeting of the Congress was 

 held to discuss the position of the Sponges in the animal king- 

 dom. Prof. Yves Delage, in opening the discussion, proposed 

 to confine his attention to the determination of the value to be 

 attached to the differences between the sponges and the 

 Coelenterates, with the object of deciding whether the sponges 

 ought to constitute a subdivision of the Coelenterates or to 

 stand apart from them as a separate phylum. He dismissed 

 shortly such features as the presence of collar-cells and the 

 absence of nematocysts, but laid special stress upon the structure 

 of the sponge larva and the relations of the parts of the 

 blastula to the permanent tissues of the adult. He described 

 how the sponge blastula consisted in its upper part of small 

 clear cells with flagella, and in its lower part of larger, granular, 

 brownish cells destitute of flagella ; and how the former layer, 

 having the histological characters of ectoderm cells, have the 

 development of an endoderm, being invaginated into the interior 

 of the other cells. After mentioning recent experiments on the 

 effect of salts of lithium and of varying temperatures on the 

 mode of invagination of the blastula in Echinoderms, he said 

 he was inclined to regard the so-called ectoderm as really an 

 ectoderm, and the cells which resemble endoderm cells as really 

 endodermal. The sponges and Coelenterates run parallel in 

 their development from the ovum to the blastula stage, but then 

 take divergmg courses. He would advocate, therefore, the 

 recognition of the sponges as a phylum distinct from the 

 C<elenterates. 



