164 BULLETIN OF THE 



nizable. The dorsal end of the stalk projects a perceptible distance 

 (Figs. 99 aud 67) within the membrane into the cell, and seems to be 

 resolved into a number of fine branches, which make their way in all 

 directions through the cell, and give off still finer processes, which anas- 

 tomose to form a network of finest fibrils. These are highly refractive, 

 and, like the stalk, take up staining fluids slightly, so that the coarser 

 branches assume a decided tint in well stained specimens. 



J^ear the stalk in the lower portion of the cell lies a stainable body, the 

 nucleus (Plate VI. Fig. 78, nl. d.) ; this is of such a peculiar character as 

 to make its right to the name nucleus appear at first sight questionable. 

 It is irregular in form, and often has a very indistinct contour (Plate V. 

 Figs. 64, 65), since a nuclear membrane can be seen only in places. 

 The lai'ger branches of the network already described connect directly 

 with the projecting angles of the nucleus, so that the latter often seems 

 to be prolonged some distance out into the cell. In the ground sub- 

 stance of the nucleus, when lightly stained, one sees a network similar 

 to that already described as existing in the cell plasma, and with which 

 it seems to be connected. There are, besides the network, at least two 

 distinct sorts of enclosures in the nucleus : first, comparatively regular 

 bodies (Fig. 64, nil.), neai'ly spherical in shape and about 5 jw in diameter, 

 which are uniformly and deeply stained, and which in every respect re- 

 semble nucleoli ; secondly, irregular bodies (Fig. 64, x), which are always 

 surrounded by a lighter area of varying width, and which thus have the 

 appearance of being shrunken. These do not stain either like the first- 

 mentioned bodies or like the rest of the nucleus itself, but in depth of 

 color are half-way between the two. What these enclosures may be I do 

 not know, but I believe the larger mass itself to be the nucleus, despite 

 its peculiarities, and I regard the dark round bodies enclosed within it as 

 nucleoli. It may be urged in this connection, that the very irregular 

 form of the nucleus makes it impossible to cut the surface perpendicu- 

 larly for more than a short distance, and that an oblique cut would make 

 the membrane very indistinct. This probably accounts for its apparent 

 absence in places. 



It is possible, I think, to furnish at least a partial explanation of 

 these peculiarities. Evidently the cells contain a highly fluid plasma. 

 This is shown by the small quantity of solid matter found in those that 

 have been " fixed," and by their variation in size. This condition might 

 indeed be expected on purely physical grounds, since the cells float en- 

 tirely free in the fluid which fills the anterior chamber. If however 

 cell and nucleus contain more fluid than ordinarily, the curious appear- 



