292 BACTERIOLOGY 



a rule, but the cell may otherwise remain normal, or it 

 may become vacuolated and finally converted into a cyst. 

 The cancer cells in the neighbourhood do not show greater 

 signs of activity than those elsewhere (Boyce), but on the 

 other hand the parasites are most numerous in rapidly- 

 growing cancers, in newly-started secondary tumours, and 

 at the growing edges and outlying parts. 



The ' parasite ' itself does not seem to be very hardy, at 

 times appearing eaten away ; and Buffer and Walker have 

 also seen it attacked and destroyed by leucocytes, which 

 sometimes surround it and sometimes penetrate into its 

 interior. 



The body, therefore, is treated as a foreign substance 

 in the tissues, looks like an organised structure, competent 

 zoologists (Balbiani and Metschnikoff) have pronounced for 

 its parasitic nature, and appearances resembling germination 

 have been observed. It also stains unlike normal cell-con- 

 tents, resembling in this, as well as in some other respects, 

 known sporozoa. On the other hand, it differs both in size, 

 durability, and some other particulars from the protozoa 

 with which it can best be compared, has never been seen in 

 an amoeboid stage, and its sporulation is scarcely fully 

 established as yet. Finally, cultivation has not yet suc- 

 ceeded, although certain bodies of a doubtful nature have 

 been observed by Ballance and Shattock l to undergo multi- 

 plication in a piece of scirrhus of the breast kept at incuba- 

 tion temperature. The opponents of the parasitic theory 

 refer it to one of the following classes, with which it 

 certainly seems to have at times been confounded : 2 trans- 

 verse sections through two cells, one of which is invaginated 

 into the other ; leucocytes, or red corpuscles, enclosed in 



1 Eeport of debate at London Pathological Society, Brit. Med. Journ.,. 

 March 11, 1893, p. 520. 



2 See Galloway, loc. cit. 



