78 LEISHMAN BODIES AND LEISHMANIASIS 



getting abundant growths of the parasites in the intestines of 

 the bugs after they had been fed on infected blood. When 

 sucked up by the bugs, the Leishmania-l&den cells in the blood are 

 digested and the parasites set at liberty in the stomach. Here 

 after several days they begin to go through their remarkable 

 transformations and active flagellated Herpetomonas forms de- 

 velop similar to those which occur in artificial cultures (Fig. 14, 

 F to O). After several days of free active life the parasites 

 round up again, lose their flagella, and are then presumably 

 ready for inoculation into a new host. All these changes occur 

 during a period of 12 days. Patton has not, however, shown 

 that the bedbug is capable of transmitting the parasites to other 

 victims by means of its bites, though it is possible that scratching 

 of the bites 'and crushing of the bugs might cause infection. 

 Developmental stages have also been traced in the mosquito, 

 Anopheles pundipennis, but here again there is no proof of the 

 insect's method or power of transmitting the parasites to new 

 hosts. The facts connected with the spread of the disease in 

 India seem to favor the theory of transmission by a household 

 insect. Rarity of the parasites in the circulating blood has been 

 claimed as an argument against the insect transmission theory, 

 but Patton has shown that almost every smear of blood from an 

 infected person contains white blood corpuscles with the Leish- 

 man bodies in them. On the other hand the manner of spreading 

 of the disease in Sudan is rather opposed to a theory of insect 

 transmission, and it has been suggested that infection may take 

 place through the medium of contaminated water .or food, since 

 experimental animals occasionally become infected when fed on 

 infected material. The suggestion is also made that an intestinal 

 wound of some kind may be necessary to allow the entrance of 

 parasites into the blood and organs of the body. Bodies re- 

 sembling Leishman bodies have been found in the faeces of in- 

 fected persons, so that faeces may in some way have to do with 

 the transmission of the parasites. The difficulty experienced in 

 inoculating the disease into experimental animals makes the 

 investigation of its transmission very difficult. The parasites 

 develop readily in artificial cultures at relatively low tempera- 

 tures, presenting the series of changes shown in Fig. 14. These 

 forms are practically identical with those found by Patton in the 

 intestine of the bedbug and undoubtedly represent part, at least, 



