384 FAMILY: TRYPANOSOMIDiE 



inoculated from the lizard's intestine into the skin of the monkey, 

 produces a lesion resembling oriental sore, in which leishmania forms 

 of the parasite occur. The evidence that the flagellate of the lizard 

 is actually that of the bug is not quite convincing. 



Phytomonas davidi (Lafont, 1909). — The flagellate has been studied 

 most fully in Portugal by Franga. He has discovered the invertebrate 

 host of the flagellate, and has described what he regards as its cycle of 

 development. As observed in the latex, P. davidi has the usual lepto- 

 monas structure (Fig. 181). The body measures 16-5 to 19-5 microns 

 in length by 1-5 in breadth. The extremities are tapering, and the 

 flagellum measures from 10-5 to 16 microns. A peculiar feature seen in 

 some of the organisms is a twisting or folding of the posterior portion of the 

 flat, blade-like body of the parasite two or three times round its longitudinal 

 axis (Fig. 184 E). That this twisting is merely the result of the medium 

 in which the flagellate is growing is demonstrated by an observation of 

 Shortt (1923) that if Leptonionas ctenocephali of the dog flea is inoculated 

 into a small fissure made in a Euphorbia, the flagellates persist there for 

 six days, during which some of them become longer, and show the same 

 twisting of the posterior part of the body. The nucleus usually lies at 

 the junction of the anterior and middle thirds of the body, with the kineto- 

 plast about 3 microns anterior to it. Shorter flagellates are also seen, 

 and even round leishmania forms. Multiplication is by the usual method 

 of longitudinal division. 



Culture of the flagellate was attempted by Fran9a (1914) without 

 success, but Nieschulz (1924rf) has successfully cultivated and maintained 

 on blood agar a strain from Euphorbia cereiformis received from Franchini. 

 He refers to the flagellate as Herpetomonas euphorhiw. 



Inoculation from plant to plant was attempted by Noc and Stevenel 

 (1911), who claimed to have transmitted the infection to healthy plants 

 by injecting material with a glass pipette. As the local inoculation 

 seems to have produced a generalized infection in forty-eight hours, there 

 would appear to be some doubt as to the accuracy of the result. Fran9a 

 (1914), trying the same experiment, after over a hundred failures, only 

 succeeded twice in producing a localized infection of the plant. As a rule, 

 the natural infection is found only in certain parts of the plant, and it 

 spreads gradually from twig to twig. Instead of its usual white appear- 

 ance, due to the presence of starch and other granules, the latex becomes 

 a clear liquid, in which these substances are not found. In sections of 

 the plant, the flagellates occur in enormous numbers, sometimes as 

 veritable emboli, in the lactiferous tubes, in which the latex has been 

 completely changed in character. This alteration not only brings about 

 the death of the infected part of the plant, but eventually causes degenera- 



