174 PROTOZOAN PARASITISM 



flagellar organelles being probably newly formed from 

 the divided blepharoplasts. 



TRANSMISSION, HABITAT AND EFFECTS 



That Chiloviastix mesyiili becomes readily trans- 

 mitted is shown by its widespread relatively high 

 prevalence. Once looked upon as a tropical parasite, 

 and possibly still to be regarded as of higher incidence 

 in warm regions where sanitation is poor, it is able 

 to survive more rigorous climates and to spread in 

 disregard of modern sanitary facilities. The increase 

 shown by Thomas and Baumgartner in institutional 

 life indicates person to person passage, no doubt by 

 unclean personal hygiene and the handling of food 

 by carriers with unclean hands. 



The fact that it has a cyst indicates this as the 

 resistant and transmissible phase but it is not cer- 

 tain that the trophozoite may not pass to establish- 

 ment in a new host, even through the stomach, in 

 naked form. Experimentally it has stood exposure 

 to hydrochloric acid even better than has Trichom- 

 07ias hommis, which is believed to necessarily pass 

 the stomach in active form. It withstood 0.1% 

 and 0.2% solutions of the acid in 0.9% sodium 

 chloride solution and was active after IVo hours, but 

 not in 0.3%. The active forms are almost immedi- 

 ately destroyed by water and they probably are not 

 transmitted in that medium, although the cysts may 

 be. 



