LEISHMANIA DONOVANI 421 



received iu Turin an infected dog from Tunis. This dog was placed in a kennel with 

 another dog, unfortunately not examined, which was afterwards found infected. 

 The brothers Sergent, Lheritier, and Lemaire (1912) allowed a pup, previously 

 examined and found uninfected, to be bitten eighty-two times by fleas fed one to 

 eight days previously on an infected dog. The pup was later found infected. Care 

 had been taken to keep the pup free froin ectoparasites. The experiments of Basile, 

 apart from any doubt one may have on account of his uniformly successful results, 

 may be criticized from the point of view of the difficulty of excluding with any degree 

 of certainty a previous infection in these animals, though the author claims to have 

 done this. During the long incubation period of a leishmaniasis it is almost im- 

 possible to exclude other sources of infection. The same remark may apply to the 

 experiment of Sergent and his co-workers. In many cases it requires exhaustive 

 study and examination to detect a small infection in an animal when it has been 

 killed, but the difficulty is increased a hundredfold when the animal is alive, and 

 reliance has to be placed on puncture of the organs. It is almost impossible to 

 perform a spleen puncture on a dog during life, while liver puncture is most unreliable 

 as a means of revealing an infection. 



Working in Malta {1914rt), the writer carried out a careful exjDeriment. Four 

 young dogs were sent from England by sea, and, on arrival in Malta, two were placed 

 in a flea-proof cage and two in an exposed cage near the other. Over 400 fleas were 

 then transferred from an infected dog kept in another part of the town to the flea- 

 proof cage. Within three weeks the dogs appeared evidently ill, and between five 

 and six weeks after exposure to infection they both died within a day of one another. 

 They were very emaciated and ansemic. No trace of leishmania infection could be 

 detected, and the jjost-mortem appearances were quite unlike those of kala azar in 

 dogs. The organs were very pale, and the spleens reduced in size and almost white. 

 The animals had died of aniiemia through abstraction of blood by the fleas, which had 

 multiplied to an enormous extent. The two control dogs remained perfectly healthy. 



Basilo (1911) first announced that the dog flea fed upon spleen juice containing 

 leishmania became infected with cultiiral forms of the parasite. It may be remarked 

 that it is extraordinarily difficult to induce fleas to feed on such material. The 

 writer has always failed after many attempts. Basile then claimed to have found 

 flagellate forms of leishmania in the human flea. In criticism of these statements, 

 it was pointed out that fleas were liable to natural leptomonas infections, and Basile 

 then qualified his statements by claiming to be able to distinguish the natural 

 leptomonas of fleas from those forms derived from the leishmania. It was evident 

 he had not excluded the natural infections of the fleas before placing them in contact 

 with spleen juice containing leishmania. For the study of flea infections, NoUer 

 (1912rf) had introduced a method of controlling fleas by fixing them on fine wire. 

 The writer has employed this method with very good results. Basile stated that he 

 had used this method in one exiieriment, and that in two days 200 fleas from an 

 infected dog were fixed on wire in this manner. On the third day they were all fed 

 on a newly-born pup, and the faeces they passed while feeding were examined. Three 

 of the fleas were found infected with leishmania. The two more heavily infected 

 fleas were then dissected and the gut contents injected into two mice, one of which 

 was found infected fifty-six days later. The fixing of a flea on wire is a delicate 

 operation which requires much experience, and may take as long as half an hour. 

 The feeding of the flea till it passes faeces on to a cover-glass, which is then m.ade into 

 a film and stained, may occupy ten minutes or as much as an hour. It is incon- 

 ceivable that Basile tethered 200 fleas and examined them in so short a time. 

 Furthermore, if his object was to discover infected fleas, this could have been more 

 quickly done by simple dissection. The object of Poller's method is to enable 



