CYTO-DIAGNOSIS 



239 



made. There is no criterion (other than certain mitoses, which, 

 as far as I know, have never been made out in an exudate) 

 by which an isolated malignant cell can be distinguished from an 

 active endothelial cell. In some cases, however, the masses of 

 cells, which can be seen to be solid and several cells thick* occur 

 in the exudate mixed with red corpuscles and a few leucocytes. 

 These cells are variable in size, usually stain deeply, and often 

 have a well-marked nucleolus. In the figure shown (which comes 

 from the ascitic fluid in a case of carcinoma of the ovary) the 

 resemblance to an alveolus of carcinoma as seen in a section is 

 very distinct (Fig. 53). 



Fig. 53. — Malignant Masses in Ascitic Fluid. 



In other cases, and much more frequently, these masses are 

 absent, and their place is taken by large endothelial cells (often 

 many times larger than a red corpuscle), which can be seen in a 

 wet preparation to be in various stages of fatty and other forms 

 of degeneration, and which in dry preparations are found to be 

 extensively vacuolated (Plate X., Fig. 3), and often contain 

 ingested red corpuscles. These may be arranged in masses, are 

 mixed with red corpuscles, and perhaps a leucocyte or two. 



Some writers consider these cells to be growth-cells, but on 

 what grounds I do not know. When they form masses they are 

 always one cell thick, never solid alveoli ; and, more conclusive, 



* As shown by focussing up and down whilst examining a wet specimen, so 

 as to obtain a series of " optical sections." 



