24 k. MLTSUKUl.'!. 



TIk' ullantui.s Ims not yet in this ^tnge entirely covered the 

 amnion and the eml^ryo from above so that tlie amnion witli its 

 sero-amniotie eonnection, and the anlei'ioi" dorsal part of the eiiilirvn 

 are visible beyond the margin of the middle allantoic lube. Tiie 

 amnion at these stages does not iit itself ti^btlv over tlie embrvo but 

 leaves a spacious amniotic cavity arcnind ilie embi-vo. ]']speci;ill\ 

 there is a remarkable snout-like prolongation of the amnion extend- 

 ing in front of the head. 



Fig. ()8 represents an embryo about forty days old. The 

 allantois has now spi-ead over a lai'ge part of the uj)per half <jf the 

 Volk, and this extension is due mostly to the right and left lobes and 

 iKJt to the middle lol)e. A j)eculiarly sharp demarcation between 

 the middle and left lobes of this stage is due to the fact that the 

 sero-amnioti<' c(»nnection is placed between them. The remnant of 

 the posleri<jr tube of the amnion appears as a white triangular ])alch 

 extending to the left at the head of the ])osterior incision. The long 

 white streak extending from the same point ol)li(jUely backward 

 over the back of the endjry»j i^ the sim[)le incision of the allantois 

 referred to above in Fig. 12 (PL TL). The allantoic vesicle being 

 of some thi<'kiie>>. the walls of tin incision which extend from the 

 iiiiM'f tii the outer limb of the allantois are of some depth, and 

 beim: pressed from abo\c are bent down and show as a wliite conical 

 streak of peculiar a p})eara nee. Note also the deep anterior constric- 

 tion with the right set of allantoic vesseU at its bottom. 



ll may be remarked in passing that the position of the embr\o 

 on the Volk is not necessarily as in Fig. 68. fhe embryo is formed 

 at ai]y jjlace which liappens to be up[ierm!)st when the egg is 

 dej'(),xitcd. ll' an egg haj»pens to stand on it> end, the embryo Avill 

 (jccupv the eml oj' the oljlong yolk. 



Fig. Gl' (^I'l. \ 111.) giA'cs a side \iew of a somewhat oldi'r 



