122 NATURAL SCIENCE. August. 



science in this period were upon vertebrate morphology. One may 

 notice here the singular circumstance that although an' immediate 

 result of Darwinism was a great increase in embryological investiga- 

 tion, Huxley contributed little or nothing to it. 



The first important paper he published was communicated to the 

 Royal Society, in 1894, ^y Stanley, the Bishop of Norwich. This 

 was the well-known account of the morphology of the Medusae. He 

 showed that these were composed of an ectoderm and an endoderm ; 

 that they were all possessed of thread-cells ; that the generative 

 organs were external. He united them with the hydroid and sertu- 

 larian polypes, and thus laid the foundation of the Coelenterata. He 

 compared the inner and outer layers of the members of this group 

 with the serous and mucous layers of the vertebrate embryo. Thus, 

 although in later days he made little further contribution to em- 

 bryology, it is to him that one of the most important generalisations 

 of embryology is due. In 1851 he contributed to the Proceedings of 

 the Zoological Society an almost equally important set of memoirs 

 upon Ascidians. He verified Chamisso's discovery of alternation 

 of generations in Salpa and Pyrosoma ; a discovery upon which 

 doubt had been thrown. He described the endostyle in these, 

 and stated, for the first time, that it was a structure common to all 

 Ascidians. He discovered the true nature of Appendiculavia, which 

 Chamisso had united with Cestuni veneris, Mertens with the 

 pteropods, and of which Mueller had stated his inability to discover 

 the affinities. He had read and been interested by Von Baer's theory 

 of recapitulation, but he went beyond Von Baer, and made use of the 

 doctrine in the modern fashion. Von Baer implied no more than the 

 existence of a closer resemblance between embryos than there is 

 between adults of different groups. Huxley compared the adult state 

 of Medusae with the larval state of higher animals ; and he pointed 

 out that Appendictilaria typifies the larval condition of other ascidians. 

 It must be admitted, however, that although in these particular cases 

 he had reached the recapitulation theory, the doctrine as such was 

 not present in his mind. For, in 1853, ^^ ^^^ Royal Institution, we 

 find him stating in so many words the view of Von Baer, " An insect 

 is not a vertebrate animal, nor are its legs free ribs (as Geoffroy 

 St. Hilaire thought). A cuttlefish is not a vertebrate animal doubled 

 up. But tliere is a period in the development of each when insect, 

 cuttlefish, and vertebrate have a common plan." 



Lecturing at the Royal Institution in the same year, he ex- 

 pounded another important generalisation that has become a common- 

 place of modern biology. He identified the protoplasmic part of the 

 cells of plants with the protoplasm of animal cells, declaring that the 

 material in which the life of animals and plants resided was identical. 

 He distinguished between the morphological and the physiological 

 aspects of Schwann's cell-theory. From the anatomical point of view, 

 he declared the theory to be of fundamental importance, agreeing with 



