f>ßQ HIROTA ; OX THE SERO-AMXIOTIC CONNECTION, 



Let US now torn to tlie two arteries which c;uise disturbance in 

 the allantois. One of them is the terniiiial part of the left allantoic 

 arterv. This artery, emerging from the umbilicus, runs along the 

 inner limb towards the right in Fig. 14. It leaves the face repre- 

 sented in that figure on the right side low down, and running alorig 

 on the other face, it enters the fio'm-e as^ain at the rio-ht side above. Ft 

 runs all this while along the inner Hmb and continues to do so until 

 it reaches tlie point A in Fig. 15. From this point, it begins to rise 

 along the line A V) and emerges on the outer limb at the [ioint 15. 

 The terminal portion of the left allantoic artery in thus passing from 

 the inner to the outer liml) causes the same sort of disturbance as was 

 made by the allantoic vein, but to a, smaller extent, and produces 

 I he fold AlUJ (in Figs. 15, K^i, 17, and IS) which is marked on the 

 outer allantoic limb by the line C B. This is therefore a sectmdary 

 disturbance of the interallantoic septum. 



Another minor septum is produced by a Ijranch of the right 

 allantoic artery. This artery proceeds from the umbilicus towards the 

 left in Fig. 14 along the inner limb until it reaches the })oint Z (Fig. 

 15), giving off branches on its way. At the ]joint Z it begins to leave 

 the inner limb and rising gradually along line Z Y reaches the (jutcr 

 limb at the point Y, from which it is distributed on that limb. 44iei-e 

 is thus produced a. mesentery -like f )ld, Z YS,' of the allantois embrac- 

 ing the vessel along the line Z Y. (Cf. Diag. 9, A.) A secondary 

 complication is produced by the fact that tlie surface of the fold is 

 slightly curved, aiid is two layered in the area W Z Y (Fig. 15). 



There are many individual variations in the configuration of 

 the primary and minor septa, but the egg explained above in full 

 may be taken as tlie ty])ical one, and all the other cases can be ex- 



1. A minor scptniii. ciuisod li.v iinothcr Imiuch of tlie riolit alhintoic artery, which proiliiccs 

 still further eouii)lic;ition in this septum, is here. t'<>r the sake of simplicity n^'t referred to. 



