Experimentation on the oral infection of pébrine was performed by the larvae from the 1st day of the 3rd instar to the 3rd day of the 5th instar. It was revealed that the larvae, the 4th instar just after molting, can produce cocoons and eclose, if they are slightly infected with spores less than about 2, 000 in number per larva, and that the larvae, the 3rd day of the 5th instar, even if they are infected with abundant spores, can make cocoons and eclose. Both of them apparently showed no symptom of disease. The number of spores contained in faeces discharged from diseased larvae, however, is generally very few, on an average 0.2 spores per field, when faeces are ground and observed. Therefore, the condition which brings about diseased silkworm moths may be explained as follows. Diseased silkworm mother moths with pébrine which lay hereditarily diseased eggs are derived from larvae slightly infected with spores per os during the larval stage from the 1st day of the 4th instar till ripening.
Water content of adult body was measured on several kinds of bean weevil attacking stored beans, namely Bruchus rufimanus, Callosobruchus chinensis (two geographical strains), C. maculatus (three strains), C. analis, C. phaseoli, C. rhodesiensis?. and Zabrotes bifasciatus. The change in water content of the body with the lapse of adult life and its sexual difference were different with the species, but these were almost the same within the geographic strains of a species. Among these species or the strains in each species, reciprocal relation was found between the body weight and the water content. Bruchus rufimanus which feeds on the succulent seed of growing plant in the larval stage was most heavy in its body weight and lowest percentage of water content, while the relation turned vice versa in Zabrotes bifasciatus whose larva feeds mainly on dryed seed under stored condition. Five species of genus Callosobruchus took their intermediate situation between these two extremes.