PROTOZOA IN CARCINOMA. 195 



l^'he next series of researches of importance in the history of 

 parasitic influences on cancer were undertaken as a result of the 

 great additions which were made to our knowledge of pathological 

 processes by the investigation of the pathogenic fungi. 



After this period, the question of the parasitic origin of carci- 

 noma seems to have been considered, in most quarters, as one of 

 those which for all practical purposes was settled definitely in the 

 negative. About the year 1888, however, the current of opinion 

 began to change, taking a somewhat different channel. Increased 

 attention was being paid to the lowest animal organisms, which 

 had been long overlooked on account of the great interest which 

 had been taken in the corresponding group of the vegetable king- 

 dom, and the influence of these as possible factors in disease began 

 to be more carefully studied. 



On looking over the numerous papers written on this subject,* 

 and especially by comparing the figures given by their authors, the 

 conclusion which must inevitably be drawn is that the bodies des- 

 cribed are of the most diverse character, and that undoubtedly 

 many forms of cell and nuclear degeneration have been made to 

 do duty as parasites, or are mentioned by the writers as having 

 been described as parasites. 



The Existence of a Parasitic Protozoon in Carcinoma. 



Having accounted to myself for many of the peculiar structures 

 described by various writers, there still remained one series of 

 appearances which remained to be identified. I now refer to the 

 cell inclusions which have been noted by various authors. After 

 having investigated the matter for some time, and examined a large 

 number of different cancers, I had become still more sceptical than 

 at the outset of being able to identify any structure which might 

 be considered with any degree of probability to be parasidc in 

 character. When I was able to define this body, however, it 

 became obvious that something totally different from the appear- 

 ances already noted was under observation. Since that time I 

 have examined a number of cancers from different regions — breast, 



* For the bibliography of this subject refer to papers by Stroebe, Central- 

 blatt f. path. Anatomie u. allg Pathologic^ Bd. ii, 1891 ; Ruffer and Walker, 

 Journal of Pathology^ vol. i, 1892. 



