130 PROTOZOAN PARASITISM 



were below forty and 83% were below fifty. The 

 later years of life increase the liability, perhaps from 

 cumulative contact and infection, perhaps in relation 

 to certain other states which are more concerned with 

 later life. 



One of these possibly related states is that of rela- 

 tive or actual gastric anacidity. Thirty-two per cent, 

 of the parasitized patients showed no free hydro- 

 chloric acid, w^iile this condition was present in but 

 19% of the flagellate-free. On the other hand, 25% 

 of the flagellate-free showed hyperchlorhydria, while 

 this was the case in but 10% of the flagellate hosts. 

 The remainder, 57% of the parasitized and 56% of 

 the free, in round numbers, were in the normal region, 

 counting broadly any acid up to fifty degrees as "nor- 

 mal." Does this more frequent finding of hyper- 

 chlorhydria in the flagellate-free and of achlorhydria 

 in the parasitized mean that flagellates are instrumen- 

 tal in pathologic states which lead to decrease in acid 

 secretion, or does lowering of the acid barrier in the 

 stomach explain the higher incidence of the flagel- 

 lates? Experimentally Trichomonas homiins had a 

 few survivors in 0.1% hydrochloric acid in 0.9% 

 sodium chloride solution at the end of two hours in- 

 cubation. It w^as entirely destroyed within this time 

 by stronger acid solution. Chilomastix viesnili sur- 

 vived acid exposure even better than did T. ho minis, 

 being still active at one and one-half hours in 0.1% 

 and 0.2% HCl in 0.9% NaCl solution, but 0.3% acid 

 killed within one half hour. Giardia intestinalis 



