290 D. D, CUNNINGHAM. 
due to abnormal conditions of the intestinal contents, permitting 
of the occurrence of processes of rapid multiplication. 
9, Normal human excreta do not form a medium in which any 
farther development of the parasitic elements outside the host- 
body can occur. 
10. On the contrary, the normal series of fermentative changes 
through which the excreta pass after exit from the body ensures 
the complete destruction of the parasitic elements. 
11. No such destructive effect, however, is exerted by the 
changes occurring during the decomposition of the excreta in 
certain lower animals —specially cows and horses; and here the 
parasitic elements on their escape from the body undergo farther 
processes of development resulting in the production of repro- 
ductive bodies securing the continuance and diffusion of the 
species. 
12. Such excretal matters, therefore, serve as a constant 
source whence parasitic elements may be transferred to the 
bodies of other animals. 
13. Human excreta which have passed through the initial 
processes of decomposition, and which have thus become alka- 
line, allow of the continued existence and multiplication of 
elements of the parasite which may then obtain access to them, 
and may thus serve as a second centre of reproduction. 
14. The introduction of the reproductive elements of the 
parasite into the human body is mainly effected through the 
medium of the air. 
15. The introduction of the reproductive elements per se 
seems to be quite innocuous. 
16. The special association of the parasite with intestinal 
disorders appears to be dependent on the abnormal condition of 
the intestinal contents allowing of the rapid multiplication of 
reproductive elements which may obtain access to them. 
Catcutta ; November, 1879. 
