CHORIO-ALLANTOIC GRAFTS. 315 



than in those where the otocyst and mesencephalon are used in 

 transplantation. Despite the disorganization produced by the 

 manipulation and by the forces acting on the graft during its 

 growth on the host, the results of the isolation are not marked, 

 differentiation occurin; s r in an approximately normal manner. 

 The absence of the external limiting membrane of the mesenceph- 

 alon, for example. doe- not alter the differentiation of the parts 

 ich. but doe- modify the type of development obtained by the 

 on. a who'. 



Be ring thea point- in mind, we may say that the-e iv-ults 



empha-i/e the mosaic type of the development of the primordia 



mined, after their origin in the embryo. The time of their 



in varies, but once they are physiologically con-tituie<: 



Mich, their i-olation from the adjacent structures has little i-liect 



on the unfolding nature of the reali/ation of the potentialities 



of their coii-tituent part-. The limits which are impo-ul on the 



(le\elo|iinent of the-e transplanted organs are dependent <>n 



en\ iiouineiit.il condition-, apparently largely of a mechanical 



nature. I nature of the development of the different cell- i- 

 app.itvntlv v< cific, but to what degree, remain- the subject 



f..i further iiiNe-iuaiioii- which are l>eing made at the pre-eiit 

 time. 



V. LITERATURE CITED. 



Atterbury, R. R. 



'23 1> Mctanepliric Anlagc of tl. in Alia: 



Am. JOUMI. Ai: KI. 



Beard, J. 



'86 1 liial Sense Organs and tlK-ii A Ganglia in 



1. lain. ; :t. Journ. Micr. Sci., XX\'I. 



Child, C. M. 



'21 1 .1 uii'l I )i-\ i-lupment of the NVt tem. I aiv. of Chi. 



Pi 

 Cohn, Franz. 



03 lite des i es Htthnchens. A;.h. f. 



Mik:. A:. .f... l.XI. 

 Danchakoff, V. 



'16 Kiuiv.il'-ii' "' Hemopoietii An] -. .Journ, '. t.. XX. 



'22 Grafts in the Allantois of Embry^ni. An'.a^. -; ol the CMiick. Anat. !' 



XXIII. Abstract. 

 Detwiler, S. R. 



'22 I \|>.-i imrnts on the Transplantation ut" Limbs of A mblystoma. Journ. 

 Ex| XXX\. 



