32 11. MlTSUKUKi. 



pD^tcrior (•(»ii.'^t ricli(jii of" (Icniiny.s — tu that caitsoil Ijy the prij.seiice 

 of the .seru-iiiJiuiutic (oiiiiectinii — is never [)roduced iii Ti'ioiiyx, 

 iilthough at the .spot whei'e it (ju;Li'ht to lie ])roduced, \\z., opp(jsite the 

 remuant of the posterior tul)e of the amnicjii, the alhiiit(jis is draw ii out 

 to a peculiarly ,siiape<l point as if it were trying;' to uo round the senj- 

 amniotic (•onneeti<ju. From these considérât ions, it follows that that 

 part of the Trionvx allaiitois in fi-oiit oï the aiilerioi- constriction 

 corresp(jiids to tiie ri<^"ht loljc of (I em m vs, the part fronî the anterior 

 (•onstrictitjn to the ptjint op])osite the I'emnaut of the posterior lid»e 

 of the amnion to the middle lobe, and the part lTo]n I lie same point 

 to the j)osteri<jr constriction to the left loljc. flic middle lohe faces, 

 as in (demmys, the sero-aniniotic conne<'tion. 



Unlike ( ' 1 e ni m y s . h o w <ô\ e r . t h e if r o \\' t h of t li e 

 middle lohe pushes, so to speak, the sero-am n i oti c 

 connection before it, so that the amnioii comes gi'ad u a I - 

 Iv to assume the shape of a bag «jf which the sero- am- 

 niotic connecti<jn forms the puckered month. Keference 

 to Fias. 25 and 2(5 (1^1. lA.) will make these ])rocesses clear. 



In Fi"'. 25, the sero-amniotic connection is still directly over 

 the dorsal side of the embryo and it is still straight. The allantois 

 is pressing on it. 



In Fia'. 26, the arowth of the amnion has removed tlie jnain 

 j)ortion of it from the sero-amniotic connection. The Avhole amnion 

 has now assumed the shape of a l)ag hanging ])cndant by the sero- 

 amniotic connection. The allantois is still pressing on the sero- 

 amniotic connection, and its i)ressure, so to speak, has bent the hitherto 

 straiafht sero-amniotic connection like the letter \. Moreover the 

 a'eneral axis of the sero-amniotic connection which has hitherto been 

 parallel with the axis of the embryo is now at right angle with the 

 latter. The general appearance of the c^^g at this stage as seen from 



