52 Bibliographical Notices. 



Chap. VII. Developpement du squelette. — In summing up a portion 

 of this chapter, M. Vogt combats the doctrine of the cranium being' 

 composed of and divisible into different vertebrae, and brings the struc- 

 ture of the embryo to his assistance ; he concludes by stating, " that 

 the cranium of the embryo does not present, like the trunk, verte- 

 bral divisions ;" and he continues, " Je dis qu'il n'existe dans le 

 crane qu'une seule vertebre, la vertebre occipitale ; tous qui est en 

 avant doitetre envisage comme un prolongement de cette vertebre, 

 destinee, comme la vertebre occipitale elle-meme, a servir d'appui 

 aux organes des sens et particulierement a, l'oreille." 



He names the maxillary and bronchial apparatus, with the tongue 

 and opercular system, " pieces viscerales de la tete," and considers 

 them not distinctly separated during the embryonic development. 

 The ventral fins do not appear until a considerable time after exclu- 

 sion. " There never exists the smallest communication between 

 these fins and the rest of the skeleton ;" and for this reason, and 

 their variable position, he considers the ventrals as locomotive organs 

 peculiar to fishes, and not as the true analogues of the posterior 

 extremities of the higher Vertebrata. 



Chap. VIII. Developpement de la peau et des mztscles. 



Chap. IX. Developpement des intestins. — Of the kidneys it is re- 

 marked, they have evidently other functions among the osseous 

 fishes than in the higher animals ; they do not correspond with the 

 true kidneys of the last, but rather to their embryonic rudiments, 

 "les corps de Wolff." This opinion already advanced is here con- 

 firmed by the early appearance of these isolated bodies, by the de- 

 velopment of their secretionary canals, and by their position and 

 extension along the vertebral column, which reminds one in every 

 respect of the " corps de Wolff." 



Chap. X. Developpement du sysfeme sanguin. — The formation of 

 the blood-cellules depends much on external circumstances : when 

 the embryos were placed in a vessel with a dark or black bottom, 

 although the general development went successfully on, the circula- 

 tion was found to be retarded, only rare and isolated blood- cellules 

 were seen in the vessels, and even the development of the blood- 

 vessels themselves seemed to be kept back, compared with other 

 parts of the structure ; on placing again the embryos in a vessel with 

 a white bottom, all the blood-vessels were filled with the blood-cel- 

 lules, and in twenty-four hours the circulation appeared admirably 

 developed. From these facts it is concluded that light has a consi- 

 derable influence on the formation of the blood, and that the cellu- 

 lary life of the embryo and the development of the organs depend 

 little on the circulation ; this pnly acquires its importance after the 

 transformation of the cellules into other constituting elements, which 

 cannot subsist or be continued without a greater or less quantity of 

 alimentary matter furnished by the blood. 



Chap. XI. Conformation exterieure de Vembryon. 



Chap. XII. Developpement des tissus en g^nfaal. — All the tissues 

 are considered to have their origin from cellules of different kinds, 



