In a previous article1 we have reported certain experiments which indicated the rôle of the body louse (Pediculus vestamenti) in the transmission of Mexican typhus fever. Since that date we have been able to confirm the results of our first investigations, and also to obtain certain other experimental data concerning the etiology of this disease. The experiments which we wish to report at present2 relate to the hereditary transmission of the infectivity of the louse and the possible rôle of the bedbug and the flea in the transmission of typhus.
HEREDITARY TRANSMISSION OF THE INFECTIVITY OF THE LOUSE
The following experiment was undertaken with a view to determining whether the young of infected lice were themselves infected. The adult louse contains in its ovaries many mature eggs. These eggs are covered with a compact shell which we thought might prove impermeable to micro-organisms. Hence it was decided to