INTESTINAL PKOTOZOA. 67 



tion, perish as soon as the temperature, which has 

 been acquired in the body, is lost ; and they cannot, 

 consequently, be considered as identical with infusoria 

 which are produced dui-ing the slow putrefaction of 

 any substance, but rather as real parasites which find 

 in the intestines the conditions necessary for their 

 existence. 



According to Dr. Davalne, who has paid much 

 attention to this subject, intestiaal protozoa are not 

 ordinarily foimd in the evacuations of healthy indi- 

 viduals, but only in those of persons who suJffer from 

 some alvine flux such as occurs in cholera, in the 

 diarrhoea of phthisical patients, and in dysentery. 



The intestinal protozoa which have been described 

 up to the present time (if we except some of those 

 which have been observed by Leuwenhock, of which 

 the nature has not been fully determined) belong to 

 three distmct genera, viz., the vibriones, cercomonades, 

 and paramecia. 



To the genus vibrio may be referred the animal- 

 culae, which have been remarked by Pouchet and 

 others in the peculiar rice-water dejections of 

 choleraic patients ; they have not hitherto been dis- 

 covered in the analogous matter which is vomited. 



Dr. Hassall believes that it is probable that these 

 animalcules are introduced into the stomach and the 

 intestines through the medium of the atmospheric 

 air, or of the water which is used for drinking pur- 

 poses, and that, finding conditions favourable to their 

 existence, they are developed and multiplied with 

 almost inconceivable rapidity. 



Vibriones have been observed, altl ough in very 

 small number, in the evacuations of healthy persons, 



F 2 



