600 



quently uncertain or quite impossible. In no other epididymes among 

 my material are such large and wide cells found. In brief, while 

 amitotic division is the rule in all ciliated cells examined, nowhere 

 else could the complete process, i. e. including cytoplasmic separation, 

 be followed; nor indeed is direct nuclear division anywhere so stri- 

 kingly evident, except in the rat and lobster. Figures 1 to 7 represent 

 a continuous portion of the wall, every cell, with one exception 

 (fig. 5), being at some stage of amitosis. The first cell is in the final 

 phase. The deeply basic-staining daughter nuclei are still joined 

 along a small area, but beyond this point on either side a new mem- 

 brane has already appeared. Figure 2 represents an early stage in 

 direct division. This nucleus is vesicular. The initial constriction has 

 begun on the lower border, closer to one pole, and progresses obli- 

 quely. The path of the ensuing fission is usually marked by a deli- 

 cate more chromatic line or thread. Figure 3 again represents a final 



I 



Figs. 8 to 12. Selected cells from an adjacent section of an efferent duct. 

 In 8 the nucleus is large and vesicular; the plane of division extends from below 

 to the left. In 9 division is complete ; this is a more common type ; the cleft passes 

 in such a manner as to divide the spherical or oval mother nucleus into two curved 

 sausage -shaped daughter nuclei, rotated in opposite directions so as to fit together 

 more or less closely \vith curved surfaces apposed (see also fig. 43). In 10 the huge 

 vesicular oval nucleus is undergoing horizontal fission. In 11 the nuclear division 

 is complete; but the daughter nuclei, one of which is vesicular the other very cliro- 

 niatic, have not yet moved apart. In 12 the division has proceeded farther, and 

 cell membranes, with inter-cellular spaces showing beyond the point of nuclear 

 separation, have appeared. 



stage. Here, however, in contrast to figure 1, the daughter nuclei 

 are vesicular; nor is there as yet any evidence of cytoplasmic division. 

 This cell, moreover, illustrates the usual condition with respect to 

 a large karyosome or nucleolus; each daughter cell usually contains 

 one such. But no such uniform procedure of an initial nucleolar fis- 

 sion as outlined in Remak's classic scheme for amitosis can here be 

 said to obtain. In fig. 4 the plane of fission is horizontal, in contrast 

 to the foregoing three where it is vertical or oblique. The daughter 

 nuclei are still closely joined along their flattened faces. These 

 nuclei will apparently have to undergo a considerable change of 



