[ 223 ] 

 By Charles Hoole. 



THE study of Parasites is one which is viewed by many minds 

 with a considerable degree of repugnance ; but on closer 

 acquaintance (not too close) that repugnance will be found 

 to give way to interest and admiration, and, as Boyle has well said, 

 " Nothing can be so minute as to be unworthy of the investigation 

 of man, which was not unworthy of being created by God." 



Now, as to the meaning of the word " parasite." In ancient 

 Greece the parasitos was a priest or minister of the gods, whose 

 duty was to collect from the husbandmen the corn set apart for 

 public sacrifices and to superintend those sacrifices. The store- 

 house in which this corn was deposited was called parasito?t. In 

 the Athenian villages certain of these parasiti, who were connected 

 with the worship of Hercules, were maintained at the public 

 expense ; but to ease the country of this burden the magistrates at 

 length compelled some of the more opulent class to take them to 

 their own tables and entertain them at their own expense. Hence 

 the word " parasite " came to mean one who frequents another's 

 table, or a hanger-on. 



Parasitism, in its widest sense, may be taken to mean the 

 dependence of one species of animal or vegetable upon another 

 for nourishment or shelter, or both. Animal parasitism may be 

 lifelong or temporary. Some parasites are free whilst young, some 

 when old, and some migrate and undergo metamorphoses. Others, 

 which have been called messmates, or commensals, only require a 

 place at their host's table, and inflict no injury upon him beyond 

 helping themselves to his food, and in some cases even rewarding 

 his hospitality with some benefit in return. Again, these mess- 

 mates may be either free or fixed, in the latter case losing their 

 organs of locomotion and even of sense, and casting their lot for 

 life with their hosts — for instance, the Ciuipedes found on whales, 

 crabs, etc. 



The parasites which feed on their host's body have been divided 

 into Epizoa and Eiitozoa — external and internal parasites. The 

 *Read before the Sheffield Microscopical Society, March 3rd, 1897. 



