226 KANSAS UNIVERSITY SCIENCE BULLETIN. 



of the necrotic area, but usually they are near the free edge of 

 the nest. 



In the succeeding section the subnest has joined the limb of 

 the main body and it was all counted together. There are 

 three necrotic areas in this section. In the lower one the two 

 directly dividing cells of that region are on the edge of the 

 degenerated area. 



A later section shows the nest in two segments, broken apart 

 from each other. A pluripolar cell division shows at one place. 



The group of cells drawn under high power in figure 15 is 

 from this section. Figure 15 shows a group of five directly and 

 one indirectly dividing cells. In this drawing and those made 

 hereafter I shall indicate the segments of the nucleus as they 

 appear through the depth of the cell, demonstrating their over- 

 lapping. The border line used was drawn at the edge of the 

 cells which presented no marked degeneration changes, but it 

 is not a hard, fast line, a few vigorous cells jutting out farther 

 than the line and a few chromatic cells being behind it. Cells 

 A, B, C, D and E show well-marked direct divisions. Cell A 

 is on the necrotic border. Cell B, a very small cell for a di- 

 rectly dividing one, is a half cell width from the necrotic 

 border. Cell C is a trifle closer than B to the border. Cell D 

 is in the third row from the border. It is peculiar in that its 

 chromatin nucleoli in each segment are not staining deeply and 

 the chromatin is diffused through the karyoplasm. Cell E is in 

 the fourth row from the necrotic edge. Cell F is an indirectly 

 dividing cell and is in the same row of cells as cells C and B. 

 Cells G and G' are the "chromatic cells" described under 

 figure 13. They mark the edge of the necrotic plug and are in 

 various stages of degeneration, as indicated by the disintegra- 

 tion of their cytoplasm and the loss of the staining power of 

 their chromatin. This sketch together with the smaller one 

 shows well this collecting of large numbers of the directly di- 

 viding cells about these necrotic areas. There are mitotic cells 

 here, but not in such proportion in comparison to their total 

 number as the amitotic. 



Figure 16. In this section there are more direct divisions 

 than indirect. There is a noticeable change in the number of 

 indirect divisions in the lower part of the nest, in what was 

 termed a "subnest" in a preceding section. In one section 

 there are nine indirect divisions, two direct. In the next there 



