226 O. C. GLASER. 



occurs in all healthy larvae, and is only a part of a normal, but 

 highly peculiar developmental history. 



Well posterior to the oesophagus, transverse sections also 

 exhibit two very distinct kinds of entodermal elements, although 

 one finds intermediate stages between them. Ventrally v and 

 partly laterally / the entoderm as compared with the dorsal 

 cells is a thin layer; the cells are granular and vacuolated, 

 especially laterally, and except where there are transition stages 

 into the dorsal cells, definite boundaries are not always recog- 

 nizable. The striking condition of the dorsally situated liver 

 cells is connected with digestion since they seem to serve as 

 temporary storage places for digested or partly digested yolk. 

 These cells are unusually large, and very remarkable in appear- 

 ance. Their contents differ greatly in arrangement, and at first 

 sight in their reactions with orange G, but such differences as 

 they present in this respect are due to the density of the mater- 

 ials, and not to any fundamental difference in their composition. 

 Certain irregular masses containing one or more large open spaces 

 and many very minute ones, tinge deeply and are frequently 

 separated by an area of considerable width from what I take to 

 be cell boundaries. These boundaries where clearly observable 

 are made up of exceedingly fine fibrils closely packed. Among 

 the other cell contents seen in this region are granules of two 

 sizes, very minute ones not always regularly distributed, and 

 somewhat coarser ones arranged in a reticulate manner. Both 

 of these kinds of material stain with orange G, though on the 

 whole less deeply than the dense masses with the large vacant 

 spaces. In the lumen of the digestive cavity are granules of 

 exactly the same staining reactions as those inside of the cells 

 and these also are arranged partly without regularity, partly in 

 reticula. Here and there are small collections of larger granules 

 that suggest from their grouping fragmented yolk spherules. 

 Since all of these materials, intra-, as well as the extra-cellular, 

 have the some staining reactions with orange G, I conclude that 

 they represent stages in the digestion of yolk. 



Laterally / and ventrally v the entoderm cells have a funda- 

 mentally different appearance from the liver cells ; they are less 

 definite on the whole in their outlines ; are decidedly smaller in 



