AXn THE FOF/l'AT. ^[EMl^RAXES, IX THE CHICK. 357 



madt* so us to supplement one imother. Fig. 14 is a surface view of the 

 membranes when the shell is removed, m which, as usual, tlie allantois 

 is coloured oreen. Fii>-. 15 iiives the outlines of the memhranes with 

 the folds in the allantois shaded. These two figures are made exactly 

 alike so that they may be superposed. Fig. 1() gives the vicinity of the 

 sero-amniotic connection on an enlarged scale. Flo-. 17 is intended to 

 give the diagrammatic rejiresentation of the allantois with its folds and 

 the interallantoic septum. In Fig. 18 the position of the amnion, 

 the yolk-sac, the albumen-sac, and the sero-amniotic connection is 

 given in addition. In the last two figures the outer lin^b of the 

 allantois is represented as extensively removed, so as to show the 

 inside of the allantoic cavity, and, in addition, the small end of the 

 egg is figured as nearly cut off from tlie main portion of the egg and 

 reflected to the left. In all the figures the egg is in one position, 

 tlie anterior lobe of the allantt^is occupying the top of the figures and 

 the posterior lobe, overlapped by it, appearing in the lower porti<m. 



At this stage, tlie allantoic lobes have not }et closed entirely o\er 

 the small pole of the egg so that the albumen-sac peeps through for 

 a small space between them at that end. How the albumen-sac 

 has thus come to lie ^^ithin the allantoic lobes is easily understood 

 if we imagine to ourselves the ])rocess explained in Diagrams 7 

 and <S to continue until the allantoic lohes have extended them- 

 selves to the small pole of the egg. Within the space thus enclosed b}' 

 the allantoic lobes, the three structures: the amnion, the yolk-sac, and 

 the albumen-sac, are disposed, roughly spe-aking, in three stories (Fig. 

 IN). The amnion with the enclosed embryo proper occupies the upper- 

 most story at the larger pole of the egg. lîelow it comes the yolk-sac 

 rallier discoidal in shape, and then the albumen-sac. The perpendicular 

 .<■//. (Fig. I'S) axial to the three stories does not ('(jincide with the axis 

 of the egg thi-(jugh its poles, but is incliiied to it as shown in tlie 



