THE PERSONAL ENEMIES OF MAN 



341 



work of Major Ross in reference to malarial fever is the best 

 illustration that can be given. It appears that a particular sort of 

 Mosquito {^Anopheles) is infested with certain stages in the life- 

 history of a parasitic animalcule i^Hcsmamoeba) which are intro- 

 duced into the blood of persons bitten. Further development is 

 there possible, serious disturbances of the system resulting. And 

 when the mosquito bites a human being whose blood harbours 

 these further stages it is in turn 

 infected. In short the mosquito 

 infects man, and man infects the 

 mosquito. Some of the details 

 are given in fig. 1239. Fortu- 

 nately the researches of Ross en- 

 able preventive measures to be 

 adopted. The early part of the 

 life of the insect is passed in 

 stagnant water (compare vol. iii, 

 p. 403), from which the immature 

 stages can be cleared out by the 

 use of petroleum, if applied at a 

 suitable time. The method has 



Malaria Parasite {Ha:via]na:ba) 



A, Two parasites within a red blood-corpuscle of man ; 

 B, one of the same branching; c, division of same into 

 minute spores: D, spores hberated by breaking up of 

 the corpuscle; when taken up into the body of the mos- 

 quito with human blood some spores assume the form E, 

 others the form F: G shows fusion of an E-spore with a 

 thread from an F-spore; h, the fusion is complete, and at 

 this stage the parasite pierces the wall of the mosquito's 

 digestive tube ; after complex changes the parasites reach 

 the salivary glands of the insect, where the stage l is 

 produced, which is introduced into the blood of a human 

 being and attacks the red corpuscles; j, the mosquito 

 [Anopheles). All but j greatly enlarged. 



been exceedingly successful at 

 Havannah, formerly a great 

 breeding-ground for yellow fever 

 and other disorders of malarial 

 type. The subject suggests an- 

 other homily on the necessity 

 for properly endowing scientific 

 research. 



Personal Enemies among 

 Spider-like Animals (Arachnida). — It need only be noted that 

 Scorpions possess poisonous stings, while some of the -larger 

 Spiders inflict poisonous bites. At one time an exaggerated 

 virulence was ascribed in Italy to the latter. Violent exercise 

 was the reputed cure, hence the origin of the rapid dance known 

 as a "Tarantella" (i.e. the diminutive of "Tarantula", the name 

 of the spider). 



The unpleasant skin-disease known as " Itch " is caused by the 

 attacks of a kind of Mite {Sarcoptes scabei, see p. 196). 



Personal Enemies among Myriapods (Myriapoda). — The 



117 



VOL. IV. 



