ON THE INFECTIVE GENITAL TUMOURS OF DOGS 133 



2. Some of the nuclei have part of their chromatin in the 

 erythrophile, part in the ordinary cyanophile condition (Fig. 53 ; 22). 



3. The great proportion of the nuclei differ in appearance from 

 those of connective-tissue cells. This point is shown in Fig. 53 ; 

 28 and 29. Associated with cells of this type are some irr mitosis 

 (Fig. 53 ; JO), which in other respects resemble them. 



4. Other cells in mitosis are apparently forming buds e.g., 

 Fig. 53 ; 27 some of which are nucleated, resembling, when 

 detached, the small nucleated bodies in 22 ; but the majority form 

 minute bodies which stain both with haematoxylin and with eosin. 



These minute bodies resemble minute protozoa in the chromidial 

 condition, and they constitute the most abundant final result of 

 the subdivision of the cells. 



Before venturing to form any opinion upon the objects seen in 

 the fully developed lesion, it is necessary to reflect that the fixation in 

 the middle of a large section is necessarily imperfect ; and accordingly, 

 before arriving at a conclusion, I have compared the appearances 

 here seen with those described above in the alveolar sarcoma of the 

 breast and other sarcomas referred to above. I wish that I had 

 been able to study also fresh scrapings of these tumours and the 

 process of granulation-tissue formation in the dog, and to complete 

 these observations in other ways; but in spite of the absence of 

 these means of investigation, which have for many years been im- 

 possible to me, I have come to the conclusion that these tumours of 

 dogs are in all probability essentially of the same nature as the 

 sarcomas of the breast, testis, bone, etc., described above. 



It may be objected that the bodies I regard as parasites are 

 much smaller in this dog's tumour than they are in the human 

 sarcoma, and, in fact, they are in proportion with the size of the cells 

 in each case, and thus would presumably be derived from the 

 cells. 



In view of this objection it must be remembered that in infec- 

 tions by coccidia it is a rule that the size of the parasites is in direct 

 proportion with that of the cells of the host, and what is true of 

 coccidia is probably true of other cell-infesting parasitic protozoa. 



