CLARK: CYTOLOGY OF CARCINOMA. 217 



than those farther toward the center. In this field the stain 

 was not as intense as that in the cells of the previous figures but 

 was of a grayish shade, and passing toward the necrotic area 

 the light in the gray increases until in cells D and D' there is 

 just enough black remaining to outline the nucleus well. From 

 this stage it gradually fades out until the cells are entirely ne- 

 crotic and do not stain at all. The cell membrane in this 

 group could not be decided upon satisfactorily. In cells A, 

 B and B' it was perfectly intact, while in cells E it seemed to 

 be entirely gone. In other cells, as C, C, the cell outline was 

 definitely preserved, while yet again in cells D and D' the cell 

 boundary was irregular and indefinite. But I am safe in say- 

 ing that when the cell has so far degenerated that the color 

 has disappeared from the nucleus the cell membrane has also 

 disappeared and disintegration immediately follows. But in 

 many of these cells the cell membrane has at least partially 

 gone while the chromatin stains deeply. The nucleus of cell 

 B' is 0.004 mm. in diameter while the chromatin mass of cell 

 C is near 0.003 mm. in diameter, showing an appreciable 

 shrinkage of this element in the degeneration process. 



The Mitotic Divisions Occur in General Upon the Periphery of the 

 Alveolus, the Amitotic Nearer the Center. 



I will use camera lucida drawings, together with tables, to 

 prove this. I counted the number of cells, the number of di- 

 rect divisions and the number of indirect, and also counted the 

 tier of cells from the periphery of the cell nest in which each 

 division occurred. I hoped by this method to arrive at some 

 conclusion as to the rapidity of growth of the tumor, in order 

 to compare it later with the growth of the adult and em- 

 bryonic mammary tissue. I also wished to decide as to the 

 relative frequency in occurrence of the direct and indirect di- 

 visions and to note, if possible, whether there was any com- 

 parison between the relative proportions of these and the sort 

 of nests in which they occurred. I also wished to decide if 

 there was a well-founded relation between either of these 

 methods of cell division and the necrotic areas indicating that 

 one or the other was related to degeneration, or that they 

 occurred equally in the same region showing that they were 

 equally vital methods of cell growth. 



Cell Nest 2 was the non-necrotic limb of a necrotic body. 

 It was counted up to the beginning of the necrotic area. I can- 



