EXTRACT XIII. A. 



ZYMOSIS WITH REFERENCES TO PARASITISM, CON- 

 TAGION, AND INFECTION. ALSO ON ENGLISH 

 AND ASIATIC CHOLERA, SO CALLED. 



PARASITISM, contagion, infection, what a combination 

 of living pests is here grouped! Yea, it is sufficient to 

 make the strongest thinking member of the human 

 family shudder and shrink! Yet we get accustomed and 

 callous, it may be, to our future avoidable, but now 

 inevitable, companionships, and can bear critically to 

 regard them as no doubt possessing some necessary, but 

 at present undetected, raison d'etre, which consequently 

 it becomes our duty to discover and turn to proper 

 utilitarian account. 



Parasites, in gaining a human home, are usually im- 

 planted or swallowed in embryo, contagia attached, by 

 adhesion to, and penetration of, the peripheral and inner 

 surfaces of the body, and infections wafted into its in- 

 terior in contaminated air, each mode of entrance originat- 

 ing an organic pathogenic agent possessed of specific living 

 qualities, enabling it to live a life of dependence on its 

 host, and to perpetuate its species, according to the laws 

 of heredity and the battle of life. 



In pursuing the subject, we shall mainly regard it from 

 the point of view of the general subject of zymosis. 



By this term, if it be permissible to use it, we mean that 

 morbid etiological process, which is continually exhibited 

 as a health disturbing and destroying factor throughout a 

 large extent of the better understood morbid entities of 



