294 Trans. Acad. ScL of St. Louis. 



elongation of the nuclear body into a pointed and a blunt end 

 (figs. 29-37), with an enlargement at its center. This 

 development into a pointed end may be abrupt as in figure 

 31, where it is seen from above, or appear as gradual (figs. 

 27, 37, 38). Of these two ends the more pointed is usually 

 the longer. The chromatin material is now seen in short 

 thick masses or bars lying on the surface ; the achromatic 

 material cannot be distinguished clearly. The bars of chro- 

 matin beo;iu to connect together into a network. The 

 nucleoli are no longer to be seen, but there appears to be a 

 red-staining ground-work or central mass to the whole 

 nucleus. The bars of blue-staining chromatin stand out 

 sharply on the surface of this red-staining central mass. The 

 further changes in the nucleus are a thickening and connecting 

 together of these chromatin bars, the lengthening and con- 

 tinued flattening of the body. In figure 41 the anterior end 

 of the nucleus appears to taper gradually towards a blunt point : 

 the posterior end is spread out into strands. In this figure 

 the cytoplasmic anterior end has become nearly one-fourth 

 of the turn while the nuclear portion has reached about one 

 and a half spiral turns. The chromatin is connected together 

 into strands with a tendency to longitudinal arrangement, 

 with crossing bars of the same material. Within this net- 

 work of chromatin there is a distinctly red-staining mass. 

 Similar proportions have been developed in figure 40. 



As the spermatozoid ripens, the chromatin mass is trans- 

 formed into a dense layer over the surface of the no\v band- 

 like nucleus, which explains Belajeff's observation that it is a 

 homogeneous chromatin mass. If, however, we examine the 

 cross-section, as he does not appear to have done, we get 

 further evidence. In figure 42 we have a drawing of an 

 actual cross-section of a spermatozoid lying in an archegonium 

 upon an egg-cell magnified 2550 diameters. The chromatin 

 here appears as a deep blue layer on the outside of a red 

 central body. The nuclear body here is seen to be flattened, 

 concave on the inner side of the coil, convex on the outer 

 side, and perhaps a little thicker at the edges than in the 

 center. The nuclear portion of the spermatozoid is about 

 forty microns in length, perhaps three microns in greatest 



