72 ANIMALS OF NO IMPORTANCE. 



is a little animal organism that enters man's blood, and there 

 grows and multiplies exceedingly, as is the wont of such 

 objectionable animals. While it is enjoying life in the blood 

 of its victim, he is suffering from fever. Now up comes an 

 anopheles mosquito who makes a meal at the expense of 

 the fever-stricken man, and imbibes a goodly number of the 

 parasites, which undergo further changes in the body of 

 their new "host" such is the term that the facetious scien- 

 tist applies to the unwilling victim of the parasite ! The 

 malaria organism then bores into the tissues of the mos- 

 quito. It is a matter for human satisfaction that the process 

 must be a painful one, at least for the mosquito. When it 

 has become comfortably esconced in the tissues of the insect, 

 the malarial germ reaches maturity and produces a fine 

 brood of young ones. These soon discover that the poison 

 gland of the mosquito is an agreeable residence. They do 

 not remain there long, for they are injected into the blood 

 of the mosquito's next victim ; then the fat is in the fire. 

 He gets fever ; and thus the cycle recommences. 



The malaria parasite, therefore, requires two hosts in 

 order to complete its life-history. If it fails to meet these it 

 pines away and dies. There are quite a number of para- 

 sites to the existence of which two hosts are absolutely 

 necessary. The tapeworm and the trichina are well-known 

 examples. The latter is the cause of " measly " pork. The 

 pig is indeed the parasites' happy hunting ground. Why 

 it is that the anopheles mosquito is the only one which will 

 serve as the " intermediate host " for the malaria organism 

 is not quite clear. Possibly the culex prefers the blood 

 plain, without the malaria sauce. More probably the cli- 

 mate of the interior of a culex is one which disagrees with the 

 constitution of the malaria parasite. Be this as it may, one 

 fact appears to be fairly established, and that is, mosquitos 

 of the genus culex do not act as carriers of malaria, while 

 anopheles do. It therefore becomes important that man 

 should be able readily to distinguish between the two 

 species. The larvas or baby-forms of culex have acquired 



