_875 



world, the author of its existence and work did not deem it necessary 

 to examine more closely into its origin, or to follow its destiny. By 

 intuition it was shown to give rise to the ganglia after it had turned 

 out not to be the point of origin of the urino-genital system as at 

 first supposed. 



In the complete work, be it remarked, I have de- 

 monstrated that the Zwischenstrang is just that por- 

 tion of the epiblast or ectoderm which takes no share 

 in the formation of the cranial or spinal ganglia, that 

 there exists no such structure as that termed by His 

 Zwischenrinne, but on the contrary in the head just as 

 in the trunk there is a Z wischenstrang^). 



My researches have embraced Elasmobranchii, Teleostei, Amphibia 

 (BYog, Salamandra, and Triton), Reptilia, Birds and Mammals. 



Part I, containing the results obtained from Elasmobranchs and 

 Birds , illustrated by six plates and more than one hundred draw- 

 ings, was sent to the press at the beginning of last April, and will, 

 I expect, very shortly appear in the Quarterly Journal of Microsc. 

 Science. 



Part II, Frog, Triton and Lacerta is nearly ready for the press. 



Part. Ill, Mammalia, will not appear for some time, for it is 

 intended to make that portion more extensive than at first proposed. 



My observations may be taken as a continuation and extension 

 of my studies on the sense organs and ganglia of the Vertebrate head 

 previously published (Quart. Journ. Microsc. Sei. Nov. 1885). 



As the starting point, and because the mode of origin of the 

 ganglia is most easily observed in that form, I will take 



The cranial ganglia in the Chick. 



Onodi's paper 2) on the development of the peripheral nervous sys- 

 tem only came into my hands after my own observations on the Chick 

 were completed. — In so far my conclusions are an independent con- 

 firmation of certain of his results on the cranial ganglia of the Chick, 

 — but only of certain of his results, for here as elsewhere Onodi never 



1) A not unnatural corollary to this is the conclusion, the proof of 

 which is easily made by direct observation, that the auditory and 

 olfactory organs do not arise „aus offen bleibenden Strecken der Ganglien- 

 rinne" as His supposes (Morphol. Betrachtung der Kopfneryen, p. 417). 



2) Onodi, Über die Entwickelung der Spinalganglien etc. Internat. 

 Monatsschrift f. Anat. u. Histol., Bd. I. 



