No. 2.] THE OVARIAN EGG OF LIMULUS. 139 



fully formed, and this is, as yet, to be observed only on the 

 tubes of the dorsal side of the animal. 



In an animal eight inches long two diverticula in cross 

 section are fully formed. 



In an animal thirteen inches long, being about half grown, 

 six diverticula are observed in a cross section of a tube. 



Here also can be seen the relation of the ovarian tube to the 

 enclosing peritoneal coat or mantle (PI. XIV, Fig. 41 ; PI. XIII, 

 Fig. 15, p.c). The germinal epithelium, with its basement 

 membrane and enclosing muscle coat, is in organic connection 

 with the peritoneal coat only along one of its sides (Fig. 41). 

 Here the various tissue elements become intimately blended, 

 and here, also, blood capillaries and blood vessels are to be 

 seen. At this point the tube increases in size, and it is here 

 that the earliest stages of the forming eggs are to be seen. The 

 epithelial cells are considerably elongated radially. At the base 

 of these cells at this point groups of closely packed, deeply stain- 

 ing nuclei can be seen. Gradually a large nucleus appears 

 surrounded by a definite cell body, which, unlike the cytoplasm 

 of the hyaline epithelial cells, is granular, and stains deeply 

 in the carmine and haematoxylin stains. No evagination of 

 the basement membrane at this point has yet appeared, but 

 the cells lying above the young egg cell seem often to be 

 bounded at their base by a definite membrane, which partly 

 encloses the space in which the young egg lies. 



On either side of this point of attachment of the ovarian 

 tube where the first stage of the egg appears, the more advanced 

 stages, in regularly increasing series, are to be seen. Passing 

 around the tube the diverticula increase with the increasing 

 size of the egg, to that point of the tube opposite the point of 

 attachment, where the largest egg in the series is to be seen. 

 There is no connection between the peritoneal coat and the 

 ovarian tube except at the one point of attachment of the latter 

 (PI. XIV, Fig. 41). The ovarian tube with its diverticula 

 hangs suspended from the inner wall of the enclosirig peritoneal 

 coat, along one of its sides. In sections the peritoneal coat is 

 seen only when the ovary is sectioned in situ, which is the 

 more convenient in the young forms. 



