206 SOME MINUTE ANIMAL PARASITES 



Unfortunately, many workers have relied on what 

 has been observed in cultures of the parasite in test- 

 tubes, amid somewhat unnatural surroundings, and 

 hence their results are less valuable, for conditions in 

 test-tubes on artificial media are not necessarily 

 criteria of what occurs naturally, as in the ali- 

 mentary canal of some biting insect or tick. From 

 the distribution of cases and the nature of the 

 malady there is little or no doubt that some insect 

 or tick, or perhaps more than one, is responsible for 

 the spread of the disease from man to man. The 

 distribution of Oriental Sore is a very wide one. It 

 is known in Europe, Asia, Africa, and America, and 

 is more prevalent in some districts than in others. 

 Consequently, there is a possibility of more than one 

 ecto-parasite being involved. Dealing first with the 

 problem of the transmitter in Asia, we find that a con- 

 siderable amount of work has been done, without, 

 unfortunately, absolutely positive results, though 

 certain insects are definitely suspected, as Leish- 

 mania tropica can develop within them. One of the 

 great centres f of -Oriental Sore in India is Cambay. 

 While the town is heavily infected, the districts out- 

 side are relatively or entirely free. Investigations 

 have been undertaken there by Captain Patton, of the 

 Indian Medical Service, and by an Indian, Dr. Row. 

 The latter investigator worked largely with cultures 

 on which he fed house-flies, but found that the 

 parasite soon disappeared from the food-canal of 

 the fly, which he considers to be a possible trans- 

 mitter of the disease. Captain Patton, working 

 by the method of exclusion, used numerous insects 



