THE ANNALS 



A\I» 



MAGAZINE OF NATURAL HISTORY 



[FOURTH SERIES.] 

 No. 86. FEBRUARY 1875. 



XTTI. — Zoologico-Emhriiolocjical Investigations. 

 By M. U8S0W*. 



** DcTeiopmental history is the true light-bearer for investigations upon 

 organic bodies." — Von Baer (Ueber die EnhcicJuhmasgeschichte der 

 TAi^-rf, 1828, Bd.i. p. 231). 



During my residence at Naples and Messina (1871-73) I 

 turned my attention particularly to the exact investigation of 

 the anatomy and developmental history of two extremely 

 interesting clas.-5es of Invertebrate animals, namely the Cepha- 

 lopoda and the Tunicata. In various species of the Cepha- 

 lopoda J studied the .structure of the female sexual organs, and 

 the formation of the ova, and then, in four species, I traced 

 the embryonal development from the fecundation of the ovum 

 up to the complete development of the young. 



In the various species of the Tunicata I endeavoured to 

 investigate : — 1, the anatomy, the minute structure, and the 

 postembiyonal process of metamorphosis of the central and 

 peripheral nervous system ; 2, the structure and in part also 

 the mode of formation of the organs of sense ; 3, the body- 

 wall (the outer and inner mantle) ; 4, the circulatory .system ; 

 and lastly, 5, the digestive apparatus, with all its glandular 

 appendages. 



As I am at present engaged in the detailed description of 

 the by no means uninteresting facts that I observed, I think 

 that a brief statement of the results obtained, such as I here 

 propose to give, may not be without its use. 



* Translated bv W. S. Dallas, F.L.S., from the ' Archiv fiir Naturge- 

 schichte,' xl. (1874) p. 328. 



Ann. <D ^[ag. N. Hist. Ser. 4. Vol. xv. 7 



