216 KANSAS UNIVERSITY SCIENCE BULLETIN. 



tegration of the cytoplasm well. While there has been a 

 swelling of the chromatin in each of these cells there has been 

 an equally great shrinkage of the nucleus, so that at this stage 

 there has been a real loss of material to the nucleus. Cell B is 

 peculiar in that its nucleus, while practically the same size as 

 normal, stains very dark; not solid, as in A, but granular. 

 There is also a faint indication of its chromatin nucleolus re- 

 maining, not indicating so much that it has become diffused 

 through the karyoplasm as that the karyoplasm itself assumes 

 a new staining power. The cell wall of cell B is broken down 

 in one place, showing signs of disintegration. Cell C, a directly 

 dividing cell, is .0093 mm. in its greatest diameter, while cell 

 D is just a trifle less than .0125 mm. The average diameter of 

 the resting cells of this group is near .007 mm. So I think 

 that a cell preparing for direct division increases in size to a 

 marked extent. 



Figure 8. This group of sixteen cells is taken from cell nest 

 6, the same nest that group 7 is taken from, and drawn from a 

 zone of cells to the inner side of group 7, that is, between 

 group 7 and a necrotic core which lies in the central part of 

 the nest. These two figures show well the transition from the 

 more peripheral nondegenerating cells to the entirely necrotic 

 mass of cell debris which fills the central portion of so many 

 of the cell nests. No dividing cells were shown. Cell A, the 

 most peripheral of the group, is the only one showing a chro- 

 matin nucleolus. It is an ordinary resting cell. In cells B 

 and B', a type of many cells found at this zone about the ne- 

 crotic area, and for that reason described as characteristic, 

 no chromatin nucleolus could be made out through the depth 

 of the cell, but in each of these the chromatin was scattered 

 through the karyoplasm in the form of a loose network, stain- 

 ing lightly. The cell and nuclear membranes were preserved 

 perfectly. Passing inward toward the center of the nest is a 

 field of cells which I have called ''chromatic cells," and which 

 are perfectly characteristic of a zone of cells that immediately 

 surrounds the necrotic core of the cell nest. They are a 

 transition stage between the normal cells and the wholly de- 

 generated ones. They resemble closely the disintegrating cells 

 described in figures 5, 6 and 7, but seem to have another history 

 of formation. As in the other cells, the nucleus is filled with a 

 homogeneous chromatic mass, the outer layers staining darker 



