603 



28 illustrates transverse constriction in a similarly shaped and oriented 

 nucleus. Figures 80 and 31 illustrate contrasting nuclear condi- 

 tions with respect to orientation and chromaticity. In cell fig, 26 

 the daughter nuclei are apparently free but still closely apposed on 

 their flat faces. The nuclei are at different extremes from the stand- 

 point of the intensity of their staining reaction. Figures 25 and 29 

 represent spiral types of direct division. In 29 the rotation of the 

 moieties has progressed to the point of a right angle, so that the upper 

 nucleus appears in side view, fitting into the concavity of the lower 

 nucleus which is seen end-wise. 



The four cells figs. 32 to 35 are selected from a separate section, 

 and illustrate three stages in the order 35 (34 more deeply basic-stai- 

 ning) 82 and 83. 



^}A^. 



16 17 



18 ^ 





' ^0 21 - 23 24 



19 22 



>->, 



Figs. 16 to 24. Portion of wall of vas efferens lined with more columnar 

 ciliated epithelium. In this particular section of the tubule. 205 nuclei were counted, 

 45 of wich were in various phases of amitosis. This collections of cells together 

 with the foregoing figures, shows that the plane of fission may be either vertical 

 or horizontal or oblique, and begin at any point on the nucleus, in either large or 

 small, either vesicular or chromatic, nuclei. Furthermore, the daughter nuclei may 

 be either chromatic or vesicular, or one may be chromatic and the other vesicular. 

 No mitoses are anywhere to be seen. Underlying the columnar cells, with terminal 

 bai-s and basal granules, are oval basal cells; these grow towards the lumen, and 

 become columnar (fig. 24) after which they proliferate by amitosis. The basal cells 

 most probably also multiply by amitosis. 



Figs. 25 to 31. Selected cells from an adjacent section of the duct. In 25 

 the division of a spherical nucleus is of the more irregular type involving a rotation 

 of the nuclear moities; in 26 the plane of fission in a spherical nucleus is horizontal: 

 in 27 the plane is vertical in an oval nucleus, whose long axis lies in the long axis 

 of the cell; in 28 the plane in a similar nucleus similarly placed is horizontal; 

 in 29 the division is again of the type shown in fig. 25, (viewed from a different 

 pole), but here the rotation has progressed to the point of 90 degrees; figs. 30 and 

 31 illustrate the non-uniformity of the amitotic division with respect to shape, orien- 

 tation, and staining capacity of nucleus. 



