BOOK I. 



PARASITES OF MAN. 



WHATEVER notions people may entertain respecting the 

 dignity of the human race, there is no gainsaying the fact that 

 we share with the lower animals the rather humiliating privilege 

 and prerogative of entertaining a great 'variety of parasites. 

 These are for the most part entozoal in habit. As the parasites 

 are apt to cause suffering to the bearer, a superstitious age 

 sought to interpret their presence as having some connection 

 with human wrong-doing. We can now afford to smile at such 

 erroneous ideas. The intimate relation subsisting between 

 parasitic forms dwelling in man and animals, and their inter- 

 dependence upon one another, alone suffices to preclude the 

 idea that parasites have been arbitrarily placed within the 

 human bearer. It would seem, indeed, that our existence 

 is essential to the welfare and propagation of certain species 

 of parasites. Possibly it is only by accepting the hypo- 

 thesis of f( Natural Selection " that we can escape the somewhat 

 undignified conclusion that the entozoa were expressly created 

 to dwell in us, and also that we were in part designed and 

 destined to entertain them. View the matter as we may, the 

 internal parasites of man and animals strictly conform to a few 

 well-known types of structure, but these types branch out into 

 infinitely varied specific forms. The vulgar mind sees nothing 

 attractive in the morphology and organisation of a parasitic 

 worm, and common-place conceptions of the beautiful cannot 

 be expected to embrace within their narrow grasp the marvel- 

 lous harmony and order that pervade the structure and economy 

 of the individual members of this remarkable class of beings. 



