164 Journal of Comparative Neurology. 



ticular critique of this doctrine in the recent investigations, 

 though it is scarcely to be expected on the part of Dohrn himself. 

 However the new investigations of the embryos of Scyllium 

 catulus of 13 mm. have revealed to him^ the mistakes in his 

 most essential observations and cast doubt upon the justness of 

 his elaborately formulated theses. Opportunity did not afford 

 for KoUiker to reply to the doctrine expressed in Dohrn's note, 

 of which I speak, at the session of the Anatomical Society in 

 Vienna for 1893.^ Nevertheless, KoUiker has presented a refu- 

 tation of the same doctrine on the part of Beard, and I am glad 

 to say that his arguments are in many respects identical with 

 those of my thesis,*' which oblige me to differ from Maurer.^ 



This observer employing my observations on the origin of 

 the lateral organs in the Selachia and Amphibia as a basis, con- 

 siders the thickenings of the ectoderm, indicated by me, as 

 germs of the nerves, which, in his opinion, are differentiated in 

 situ from the elements of the ectoderm instead of entering it 

 secondarily from the brain. He returns therefore to the stand- 

 point of Dohrn. I have already shown whether it is well 

 founded. He was not acquainted with rny last work on the 

 origin of the nerves and the formation of the lateral organs. 



The contradiction pointed out by Maurer between his opin- 

 ions and mine, relative to the development ot the nervous lat- 

 eral sense organs of the Amphibia, is due to the fact that he 

 did not observe the difference which I established between the 

 first origin of the nervous lateral sense organs and their new 

 formation. 



In the first case, as I have presented it (1. c. T. I. f. H, 



*A. Dohrn. Die Schwann'sche Kerne der Selachierembryonen. Anat. 

 Anzeiger, 12, 1 89 2. 



^A. KOLLIKER Ueber die Entwicklung der Elemente des Nervensystems 

 contra Beard und Dohrn. Ergaenzungsheft d. Anatom. Anz. 1892. 



* P. MiTROPHANOW. (a) On the Organs of the Sixth Sense of Amphibians, 

 (b) On the Nature of the Peripheral Nerve Endings, (c) On the Question of 

 Peripheral Nerve Endings. 1887. 



' F. Maurer. Hautsinnesorgane, Feder und Haaranlagen. Morpholog. 

 Jahrbuch. XVIII, 1892. 



