OF THE INVERTEBRATE ANIMALS. 5 



Chemical analysis* has proved the existence of the former, and 

 the microscope that of the latter, in vertebrate animals ; the ex- 

 traordinary quantity of peculiar fat and the large amount of 

 phosphoric acid are not found elsewhere in the animal body. 

 By the above reactions I satisfied myself, in the oesophageal 

 ring of Anodonta, Helix [pomatia) and Limnceus [stagnalis), as 

 representatives of the MoUusca, in the Craw-fish, Cockchafer and 

 geometrical spider {Epeira diadema) of the Articulata, of the 

 identity of the chemical composition of the nervous elements in 

 these different families ; so that I consider the conclusion of the 

 chemical identity of the nervous system, in the animal series at 

 least, as not too hazardous ; that nerves, which can only with 

 great difficulty be isolated sufficiently for microscopic examina- 

 tion, cannot be subjected to elementary analysis, is self-evident. 



B. Muscular System. 



As we know, two morphological muscular elements are distin- 

 guished in the vertebrate animals, — transversely-striated primi- 

 tive bundles and smooth fibres, which moreover exhibit nume- 

 rous intermediate stages, as in the heart. The question of the 

 existence of a chemical difference corresponding to this morpho- 

 logical one, has as yet neither been suggested nor experimentally 

 determined ; the latter would also be effected with very great 

 difficulty, especially with the active assimilative changes in the 

 higher vertebrate animals, the intermediate products of which 

 adhere very intimately to the morphological elements. We find 

 fewer difficulties in the more simple organization of the Inverte- 

 brata. The Articulata have transversely striated, and the Mol- 

 lusca smooth muscular elements f; nevertheless the development 

 of the two X exhibits great uniformity ; in fact, in the young 

 stages of the Crustacea we find plane primitive fibres, which sub- 

 sequently acquire the transversely-striated aspect. The next 

 question was, whether the same uniformity occurred as regards 

 their composition. I therefore separated the large thoracic mus- 

 cles of the Cockchafer, the muscles of the posterior abdominal seg- 

 ments of the Craw-fish, and the adductor muscles of Anodonta, 



• Fremy, L'Institut, No. 311, p. 435. 



t R. Wagner, Miiller's Arcliiv, 1835, p. 318. 



X For the Vertebrata, see Valentin, History of Development, p. 207, and 

 Miiller's Archio, 1810, p. 198; Scliwann, Mlkroslcopische Uiitersuchungcn, 

 p. 156 ; llenle, Jllgemeine Anatomie, p. 600. In the Cepluilopoda, A. Kijlliker, 

 Enlwickelunysgeschichte der Cep/ialopodeii. Zurich, 1844, p. 70. 



