86 Ainerican Quarterly Microscopical Jourfial. 



needs help, lest he should die on the public highway, but who 

 practices the precept not to kill the fowl in order to get the 

 eggs. It is at once seen that he is essentially different from 

 the messmate who is simply a companion at table. The beast 

 of prey kills its victim in order to feed upon its flesh : the 

 parasite does not kill ; on the contrary, he profits by all the 

 advantages enjoyed by the host on whom he thrusts his pres- 

 ence." Again: '' Every animal has its own parasites, which 

 always come from without. With some few exceptions, they are 

 introduced by means of food or drink." 



This gives us a better idea of a parasite than any single 

 definition that could possibly be given. 



They are animals : — 



1. Entirely dependent on other animals for support. 



2. They do not usually reproduce themselves in the animal 

 which they inhabit. 



3. They may locate themselves in any organ of the body, 

 having been found in the brain, spinal cord, eye, ear, heart, 

 blood, &c. 



4. They vary in size ; some requiring the microscope to 

 reveal their presence, while one has been reported to have a 

 length of three thousand feet.* 



5. They may exist in great numbers in one individual. 

 Prof. Berthold, of the University of Gottingen, in a memoir 

 on the abode of parasites in man, says that a case was re- 

 ported in 1699 where a boy twelve years of age voided 164 

 millipedes, 4 scolopendrse, 2 living butterflies, 2 worm-like 

 ants, and 32 brown caterpillars. Two months later he voided 

 4 frogs, several toads, 21 lizards, and sometimes a live serpent 

 was seen for a moment at the bottom of his mouth. Van 

 Beneden remarks : " Happily for science, we do not see such 

 things seriously related in books at the present day." He says 

 that sixty millions of eggs have been counted in a single ne- 

 matode, and in a single tape-worm, or rather in a colony, even 

 a thousand millions of eggs. 



6. They inhabit every part of the globe. 



7. As a rule, they are not hurtful ; an excess is hurtful. 



It is said that the Abyssinians never take medicine when 

 they have Taeniae, being in a better state of health at that time. 



*7>«/a solium. Reported at the Academy of Copenhagen. 



