CLARK: CYTOLOGY OF CARCINOMA. 215 



no definite form but with a more or less regular outline. This 

 mass evidently represents the nucleus, which has become filled 

 with a diffused, swollen mass of chromatin. Its cell membrane 

 has broken down, allowing the cytoplasm to flow out into the 

 surrounding intercellular spaces. Notice the regular form of 

 the chromatin nucleoli in this group of cells. 



Figure 6. This group of eleven cells was drawn from the 

 same cell nest as the previous group. Cell A is a large cell, 

 .0093 mm. in its greatest diameter. In the cytoplasm about the 

 nucleus are four vesicles, similar to those described under 

 figures 2 and 4. The chromatin of its nucleus is of regular 

 outline but is unusual on account of its size, being a trifle over 

 one-half the diameter of the nucleus itself, at least twice the 

 amount found in the ordinary resting cell. I think it is a cell 

 just beginning the degeneration process shown by the swelling 

 of its chromatin. Cell C is undoubtedly in the process of de- 

 generation, for its cell membrane has disappeared, allowing 

 the cytoplasm to flow out uncontrolled. It is a cell almost as 

 large as cell A. Its chromatin, which exists as a deeply stain- 

 ing mass somewhat irregular in outline, was larger in diameter 

 than that of cell A. The nuclear wall could not be made out. 

 Cell B is one farther along in the process of breaking up than 

 cell C, for most of its cytoplasm has gone. The diameter of 

 its chromatic element is not so much larger than that of cell 

 C but it is more condensed and of more regular outline. These 

 three cells, I think, are respectively in advancing stages of dis- 

 integration. Cell D is a cell dividing indirectly, having a chro- 

 matic mass larger than that of cell C but of a looser arrange- 

 ment, indicating individual chromosomes. It also maintains its 

 cell borders perfectly. 



Figure 7. This group of eleven cells was drawn from cell 

 nest 6 in the region of a necrotic area. Cells A and B are in 

 the fifth and sixth tiers respectively from the free edge of the 

 tumor on the peripheral side of the group. I will use this 

 group and the one following it, figure 8, to show changes in the 

 cells passing inward from the free edge of the cell nest to a 

 necrotic area. On the side peripheral to cell A there is a small 

 necrotic spot two or three cells in diameter, which accounts 

 for cells A and B on that side of the group. Cell A is a good 

 specimen of such cells as C and B of figure 6 or cell E of figure 

 5, It shows the swelling of the chromatin and the disin- 



