AMCEB^E OF DISEASE 147 



excretory vacuole. As their absorptive processes 

 need not be localized, so there is no necessity for 

 the development of a special excretory apparatus. 

 Just as the whole general surface is absorptive, so 

 can it also be excretory. Formerly a broad state- 

 ment was made that no pathogenic Entamceba pos- 

 sessed a contractile vacuole. While this is true for 

 the Entamcebce from the human intestine, yet it is 

 not so universally, since Entamceba chironomi, that 

 causes injury to the larvae of Chironomus (the 

 " bloodworms "), possesses a well-marked contractile 

 vacuole with a radiating structure. 



Increase of numbers among the Amoebae takes two 

 forms. The first consists simply of the separation 

 of buds from the body of the trophozoite or the 

 division of the trophozoite into two portions. Such 

 methods are multiplicative, and serve to increase the 

 number of parasites within the host. A budding 

 phenomenon also occurs in degenerating and senile 

 amoebae. In order to effect the transference of the 

 parasite to a new host, encystment occurs. The 

 cysts are resistant, and within them, four, eight, or 

 more spores occur. Sometimes the encystment is 

 incompletely "known, and the same is true of the 

 schizogony of several of these amoebae. 



Entamoebae are extremely important, as they occur 

 commonly in the intestine of man in tropical coun- 

 tries, and they produce dysentery and diarrhoea. 

 The Philippine Islands, for instance, were notorious 

 for the number of deaths from dysentery until the 

 United States made investigations into the cause. 

 China, Japan, parts of India, tropical America, 



