64 ESSAYS ON BACTERIOLOGY. 



vestigations of Cunningham, in India, who claims to 

 have recognized several different species of comma 

 bacilli in cholera. The value and meaning of these 

 claims remain as yet doubtful. It is interesting to 

 note the experiment of Pettenkofer, vs'^ho voluntarily 

 swallowed pure cultures of comma bacilli brought 

 fresh from Hamburg. He did this to show his con- 

 tempt for these organisms as the active cause of chol- 

 era. The result of his self -inoculation was a moder- 

 ate sickness, which he asserted not to be cholera, but 

 which less prejiidiced authorities believe to have been 

 simply a mild cholera, the discharges from the bowels 

 containing almost pure cultures of the comma bacilli. 

 Another experimenter, actuated by the same motive, 

 produced in himself similar results, except that the 

 sickness was more severe. It is of practical interest 

 also that, upon the approach of cholera to New York 

 recently, the presence of the comma bacilli in the de- 

 jections was successfully used as a test of the exist- 

 ence of the disease in suspected cases. 



2. Cancer. — Many observations have been made 

 of peculiar bodies in cancerous tissue. These have 

 mostly been placed in the class coccidia. Their in- 

 vestigation is so difficult, artificial cviltivation so elu- 

 sive, and their relation to the tissiie cells so peculiar, 

 that it is difficult to decide their biological position. 

 The question is, therefore, still unsettled. Domergue 

 is inclined to believe these coccidia to be simply cell 

 transformations. There are, however, those who take 

 a different view, who believe them to be true parasites. 



