2io SOME MINUTE ANIMAL PARASITES 



though from the point of view of medical treat- 

 ment, they may be of use for the time being. Until 

 the quest of the carrier has been accomplished, little 

 value can accrue from classifications based on in- 

 complete knowledge. Similarly, it is not yet possible 

 to pronounce with certainty as to whether Leishmania 

 donovani of Indian Kala-azar is identical with L. in- 

 fantum of the Mediterranean region, as some authors 

 consider. Leishmaniasis is constantly being re- 

 corded from places hitherto believed to be free from 

 the disease, so that the geographical distribution is 

 being extended, as in China. 



Further investigations on immunity against leish- 

 maniases will be awaited with interest, as it is already 

 known that one attack of Leishmania tropica confers 

 immunity for life against Oriental Sore, and there is 

 some evidence that inoculation with the milder leish- 

 maniases may confer immunity against more virulent 

 forms. 



