THE SPECIES OF HUMAN AMCEB^ 169 



A particularly inviting field of investigation is the effect of 

 radiant energy of different wave lengths throughout the various 

 octaves available for use, alike on infections in culture animals, on 

 amoebae in cultures, and on encysted stages. 



The biochemical problems have been noted in part in the dis- 

 cussion of the physiological ones. Specifically much may be done 

 in a precise determination of the cultural requirements of the dif- 

 ferent species, the ranges of adaptation to changes in the amounts 

 of organic and inorganic constituents of culture media, and the 

 results of substitutions. 



The cultural, serological, and immunological problems are 

 closely interlocked and are interrelated with the physiological and 

 biochemical. The prime desideratum is a method of establishing 

 and of maintaining the intestinal amoebae in pure culture, of free- 

 ing them with facility and certainty from bacteria and yeasts. 

 When this is attained the field will be opened for investigations 

 along serological lines, with precipitin and agglutination tests, with 

 immunity and cross-immunity tests, wath toxins and antibodies, 

 and with intradermal tests for infection with Endam^ba dyscn- 

 tericE and possibly for certain other species. 



In the diagnostic field much remains to be done in determining 

 the relative availability and practicability of the smear method of 

 diagnosis by cysts in comparison with the culture method. In the 

 latter method the difficulty of determining with certainty all of 

 the species in the motile phases is very great and is, with our 

 present knowledge, practically impossible. 



Protozoological work is much needed in the medical and thera- 

 peutic field in a study of the morphological changes in the motile 

 and encysted stages in stools and in cultures, resulting from the 

 action of the various drugs and combinations of drugs used in the 

 treatment of amoebiasis. The viability of both motile and encysted 

 phases at successive stages of treatment should be checked by cul- 

 tural methods. Correlations should be made between the various 

 methods of treatment at different stages on the one hand and the 

 morphological and functional changes in the parasite on the other. 

 Control experiments w4th the drugs in vitro on cultures should 

 also be made. 



The effects of the treatments used against Endanioeha dysen- 

 teries upon the other amoebae of man should also be examined by 

 comparable methods. 



