1. Smears from the nasal cavities of fifteen patients suffering from kala-azar have been examined and in nine of these typical Leishman-Donovan bodies have been found.
2. Smears from the surface of the tonsil and from the saliva in one of the above nine cases showed the presence of leishmania. The tonsils of this patient, who died as the result of kala-azar and secondary infection, at autopsy were shown to be massively infected with Leishman-Donovan bodies.
3. Leishmania in the nasal discharge of two patients were shown by inoculation into susceptible animals to be viable and capable of producing infection. Sufficient time has not elapsed to determine the viability of the organisms from the remaining cases.
4. These experiments show for the first time that a rich source of infective material from a large proportion of patients with kala-azar is available for direct transmission of the disease.
5. Strong evidence is presented as a basis for the concept that one of the natural modes, perhaps the most important natural mode, of transmission of kala-azar is from person to person by way of the upper respiratory and alimentary tracts.
6. Two normal human volunteers and numerous normal experimental animals have been inoculated into the nasal and oral cavities with the nasal discharge, known to contain leishmania, from patients with kala-azar. The results of these experiments will be reported at a subsequent date.