138 Drs Fantham and Porter, Further Experimental | 
invertebrate hosts of Leishmania, while much attention was con- 
centrated on attempts to infect the usual laboratory mammals 
with the parasite or with cultures of it. It seems, then, that one, 
important aspect of the subject of leishmaniasis unfortunately has 
been overlooked for a long time. 
Pane Material and Methods. 
The flagellates used in this research include Herpetomonasi, 
jaculum (Léger) parasitic in the gut of the Hemipteran, Nepa 
cinerea; H. stratiomyiae (Fantham and Porter) from the digestive; 
tract of the larva of the Dipteran, Stratiomyia chameleon; H. pedi-\ 
culc (Fantham) from the gut of the body-louse, Pediculus vestumenti;) 
and Orithidia gerridis (Patton) from the alimentary tract of the) 
Hemipteran, Gerris paludum. It will be seen that some of these’ 
insect hosts are blood-suckers, while others are not. 
The vertebrate hosts included sticklebacks (Gasterosteus acu-)| 
leatus) among the Pisces; newts (Molge vulgaris), frogs (Rana 
temporaria) and toads (Bufo vulgaris) among the Amphibia; 
lizards (Lacerta vivipara) anda grass-snake (Tropidonotus natria) | 
among the Reptilia, and mice (Mus musculus) among the Mammals. 
The insect flagellates were introduced into the vertebrates by) 
inoculation or by feeding. No ectoparasites and no haematozoa) 
were present on or in the vertebrate hosts at the commencement | 
of the researches. 
Blood films were made from time to time during the life of | 
the experimental animals, while smears of the internal organs: 
were prepared at autopsy. Some of the preparations were fixed | 
while moist with osmic vapour followed by absolute alcohol, while « 
others were fixed wet with Bouin’s fluid. The stains used were | 
Giemsa’s solution, haematoxylin and eosin, and occasionally iron- | 
haematein. 
Control vertebrates were kept in each case. They remained 
healthy and unparasitised, and lived longer than the experimental 
animals. ] 
Ill. Eaperimental Work. 
As experiments with mammals were detailed in our former” 
paper, it may be of interest to begin with new experiments on | 
cold-blooded hosts and then to take further experiments with : 
mammals, involving the use of flagellates hitherto untried. | 
(a) Experiments with Pisces. | 
Experiment 1 (A.P.). A male stickleback, Gasterosteus acu- 
leatus, was inoculated subcutaneously with the mid-gut of a Nepa 
cinerea containing flagellate forms of Herpetomonas jaculum. The 
