CONCLUSION 241 



to a very much more subordinate position, as it can 

 only apply to the human portion of the animal 

 kingdom, leaving the insect-carriers — the rats, the 

 birds, and other innumerable animals — free to continue 

 to SM'^arm with the parasites. 



Again, it cannot be too strongly insisted upon that 

 the study of parasitism opens our eyes to the fact 

 that the diseases of the human section of the animal 

 world form but a very small part of the great 

 subject of pathology. The pathology which parasitism 

 teaches, and which Pasteur had before him when he 

 made his beautiful investigations upon silkworm 

 disease, shows us unmistakably that the new advances 

 against disease must be made on co-operative lines, that 

 the human species must also extend its protective 

 measures to the inferior species. 



Already we see indications of this policy in the 

 teachings of modern hygiene, which insists upon the 

 importance of keeping our economic animals free from 

 parasitic diseases of all kinds. We now require to 

 broaden and extend this doctrine, if we wish to 

 eliminate parasites as a factor in keeping back the 

 progress of man. 



16 



