CHORIO-ALLANTOIC GRAFTS. 303 



Streeter (1907, i<H4 ', who has experimented extensively on 

 the development of tlu- i-.tr vesicle in the amphibian larva, has 

 noted the ability of the vesicle to develop in a nearly normal man- 

 ner v. hen transplanted to other portions of the head either of the 

 same or oppo-ite -ide. In most of the ses, it reorients itsel 

 to dorso-ventrality and retains its definite character as from the 

 right or the li-fi -idr. In Spemann's experiment- I'lio), the 

 inverted otocy-t di<l not orient itself in every ca-e, <lue. in 

 Si reeter's "pinion, to the fact that in making the large inci-ion for 

 the rotation of the vesicle, the adjacent ti->ue wa- mneh dis- 

 turbed and al-o to the f..ctor of mechanic..! pre--ure which was 

 applied to in-nre the closure of the wound. Streeter eliminated 

 the-i- !'..< tor- by makiiu -lit and stretching t hi- for the opera- 



tion, ("lo-un-aiid hi-alin^ t hus took place immediately \\ it hont 

 the applie.ition of prrtire. Spemann's results do not otherwise 

 seem to be in conflict with those of Streeter. The n-ult- of both 

 1. 1 the-e iii\ ( . -i/e the high tie. ' independent 



>elf -differentia i ion obtained by the organ. Street < r notes i-u i. 

 ' All our e\ idence points to a high decree of differenti- 

 ation <.f the cell- of the \e-icle, and it is conspiem m-ly jiro\eii by 

 their i on o| l.iier.ility, . . ." 



It will be of interest to note also a case cited b} Lewis [907 . 

 in -pe.ikiiu .-f \\hirh he -t.:tes that an otic < .tp-uh- of the \\-[. 

 Ainfilystonin. farmed .iround the membranoii- labyrinth .iri 

 fn.m tran>pl. nited tiue from Rana sylr<itii. Hi- .nld- that the 

 character of the i artilage 'ell- i- -uch .1- to determine them as "f 

 .\nibl\-toiu.il origin. !.e\\i- eon-ider- that tin- -how- that in 

 \\.i\, the otir \\--icle -tiniulate- the formation ,,f (he . 

 n- ca|-uli- around it. He says (pagl I |5 . "It t he 



tilaginous capsule about the otic vesicle is dependent upon the 



inlliu-nee of the latter for it- origin it will |>robabl\ be found the 

 'ilai^e of other tt-iii- of the einbr\'o i- like\\i-e de]-eiident on 

 ain inthience- in the neighboring -tr net lire- for it- origin Iroin 



the ine-ench\ me \ piece of trail-planted brain or a 



trail-planted e\e, for example. e\ en when I'lo-e to the cartil 

 iiini; about the otic \e-icle or central ner \ou- -> -lein do,-- not 



stimulate the formation or growth of cartil . 'in it-elf." 



In the i;raft- of the otic ve-icle de-cribed above, the c'artilage 



