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SCIENCE. 



[N. S. Vol. VIII. No. 194. 



tions : Professor Alphonse Milne-Edwards, 

 Director of the Natural History Museum, 

 for Fraace ; Professor Schulze, of Bei'lin, 

 for Germany ; Professor Hubrecht, of Ut- 

 recht, for Holland ; Professor O. C. Marsh 

 for the United States ; Professor Salensky, 

 of Odessa, for Russia, and Professor Mit- 

 sukuri, of Tokio, for Japan, after which 

 Professor Newton, Chairman of the Eecep- 

 tion Committee, acknowledged the graceful 

 expressions of the previous speakers. He 

 claimed that Cambridge attached more 

 value to zoology than did any other uni- 

 versity, and exhibited a copy of what he re- 

 garded as the first book on zoology which 

 treated the subject in the modern spirit. It 

 was published in 154 J: by William Turner, 

 a Fellow of Pembroke Hall. 



The most important features of the scien- 

 tific proceedings of the Congress were two 

 discussions, one on the position of sponges 

 in the animal kingdom, the other on the 

 origin of the mammalia. The former dis- 

 cussion was opened by M. Ives Delage, who 

 said he would limit his remarks to one 

 point in the argument. The doubt as to 

 the afiinities of sponges was whether the 

 group Spongida was to be regarded as a 

 distinct phylum which had arisen quite in- 

 dependently, or whether it was only a 

 branch of the Coelenterate phylum. All 

 zoologists admitted that the sponges lacked 

 several characters found in the typical 

 Coelenterates, but it was disputed whether 

 these characters necessitated the separation 

 of two groups. The speaker believed that 

 one of the difierences was so important as 

 to preclude the inclusion of sponges in the 

 same group as Ccelenterata. In the sponge 

 larva there were two types of cells — collar- 

 cells bearing each a long whip-like flagel- 

 lum and large rounded cells containing the 

 yolk. The former occurred at the upper 

 end of the larva, the latter at the lower 

 end. From analogy with the Metazoa it 

 would be expected that the lower cells 



would pass inwards and form the internal 

 element of the larva. But observation 

 showed that the the reverse process oc- 

 curred. Balfour thought it better to assume 

 that the observers were in error rather 

 than that such an abnormal development 

 could occur. There was, however, now no 

 doubt that the observers were correct, and 

 that two layers of the blastula stage in the 

 sponge were formed in the opposite way to 

 that which occurred in other animals. That 

 was to say; the layer which had the histo- 

 logical character of an ectoderm had the 

 evolution of an endoderm, and the layer 

 that histologically was an endoderm passed 

 to the outside and acted as the surrounding 

 ectoderm. The possibility of this reversal 

 Professor Delage illustrated hy reference 

 to experiments on the development of larval 

 echinoderms in which, by raising the tem- 

 perature, a similar inversion of the two 

 layers was sometimes produced. He, there- 

 fore, held that the change was actually in 

 the position of the cells, and not that the 

 endoderm cells had acquired the characters 

 of ectoderm cells, and vice versa. He con- 

 cluded that the sponges began to develop 

 along the same line as the rest of the 

 Metazoa, and that they separated from the 

 main Coelenterate branch at the stage cor- 

 responding to the blastula. 



Mr. E. A. Minchin, of Oxford, remarked 

 that it was not until nearly the middle of 

 the present century that the investigations 

 of Dujardin and of Dr. Dobie, of Chester, 

 proved that sponges were animals and not 

 plants. After this point had been settled 

 most observers regarded the sponges as 

 Protozoa, a view based mainly on the his- 

 tological structure of tissues. AVhen im- 

 proved methods demonstrated the relations 

 of the constituent cells this theory was dis- 

 credited; Leuckart, in 1854, pointed out 

 the sac- like form of the adult sponge, which 

 he compared to a polype devoid of ten- 

 tacles and thread- cells. Haeckel placed 



