As regards separating oriental sore from the visceral leishmaniases Gonder has shown that white mice may be infected with both kala-azar and oriental sore, there being produced in each case a general infection with the presence of parasites in spleen and liver. A point of difference, however, is that the oriental-sore mice develop lesions on feet, tail and head which was not observed with the kala-azar mice. There are some reasons for thinking that in human cutaneous leishmaniasis a generalized infection may precede the local manifestations. Dogs and monkeys can be infected with _L. tropica_ as well as mice, but in them we have only cutaneous lesions produced. Inoculation should be made intraperitoneally. A very interesting point is that the dogs in India never show a natural infection with _L. donovani_, while in the regions where _L. infantum_ is responsible for human infections the natural infection of dogs is not uncommon, indeed many think the dog the reservoir of virus for both _L. infantum_ and _L. tropica_. It has been suggested that the dogs of India, where kala-azar prevails, may be immune. _Morphology._—As regards morphology it is usually stated that the parasites of the three species of _Leishmania_ are practically identical. In cultures it has been noted that the flagella of _L. tropica_ are longer and more twisted than those of _L. infantum_. Again it has been observed that the parasites of the Oriental and South American skin lesions may at times show a flattened or band-like trophonucleus instead of the constant round or oval one of the visceral leishmaniases. Escomel has reported the finding of flagellated _Leishmania_ in the South American sores. _Relationship._—Within the past year the view has been generally accepted that Indian kala-azar and infantile kala-azar are one and the same disease, the points of difference between _L. donovani_ and _L. infantum_ which had been advanced from cultural and animal inoculation standpoints having been disproved. It has been suggested that the Mediterranean basin may have been the original focus of visceral kala-azar and that it spread thence to India by way of Greece and the Russian Caucasus, cases having been reported from districts which would join the two foci. Just as children bear the brunt of malaria in old malarious districts and adults suffer in places in which the disease has been more recently imported, so by analogy we may consider the disease as of more recent introduction in India. We now know that visceral leishmaniasis is widely distributed in China, north of Yangtse, as well as in the Sudan, and quite recently a case of kala-azar has been reported from South America, in an Italian, who had lived in Brazil from 1897 to 1910.