Anthropometrical measurements and measurements of body temperature were made in July in Naha (Okinawa, subtropical zone) on 7 young male Japanese who were born and reared in Okinawa (group O), and in July in Nishinomiya on 12 young male residents of Main Islands of Japan (temperate zone) born and reared in Okinawa (group OM) and 11 young male residents of Main Islands born and reared in Main Islands (group M). The mean value of duration of residence in Main Islands of subjects in group OM was 15.8 years. Skin temperatures at 10 sites and oral temperature of seated subjects, wearing short only, were measured in a climatic chamber maintained at 30 C and 70 per cent relative humidity after sitting in a chair at rest in the climatic chamber.
Group O showed shorter height, lighter body weight, larger girths of chest, upper arm and thigh than group OM and M. Group O showed smaller mean values of Rohrer's index and Brugsch's index and greater mean value of the ratio of body surface area to body weight. Group O showed thinner skinfold thickness and smaller percentage of body fat content than other two groups. Differences of anthropometrical measurement between group OM and group M were much less when compared with those between group O and other two groups. Mean values of oral temperature for group O, OM and M were 37.0 C, 37.1 C and 37.2 C respectively. The mean values of mean skin temperatures for group O, OM and M were 35.0 C, 34.8 C and 34.9 C respectively. Group O showed considerably smaller value of T₀-T_s gradient (2.02 C) than group OM (2.35 C) and group M (2.29 C). These results indicate that physical characteristics of subtropical natives have changed and that difference of physical characteristics between subtropical natives and temperate natives and capacity of maintaining higher skin temperature and higher conductive-convective heat transfer coefficient observed in subtropical natives were reduced by long residence in a temperate zone.

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It was attempted to cultivate Trypanosoma garnbiense (Wellcome strain), maintained by mouse-passages for years, in coexistence with the mouse L-cells in vitro at 37 C. In the system of culture the population of the cultured trypanosomes increased 3-fold in 24 hours, then decreased. The fact that the doubling time of trypanosomes was longer in the culture system than in an infected mouse seemed to be related to the suppressed division of parasites. It was observed that the final stage of parasite division, that is, the cytoplasmic separation into 2 individuals was much prolonged in culture, although the kinetoplastic, nucleal and flagellar duplication was carried through without suppression. In the control without the L-cells, no multiplication of trypanosomes took place. Infectivity of the cultured trypanosomes to mice did not change throughout the course of culture, at least until the time of the maximum growth of parasites. The subculture of trypanosomes was not successful.

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A new apparatus for feeding mosquitoes is described. It is constructed without special technique and easy of handling. The usefulness of the apparatus is demonstrated by a report on investigations into the effects of nucleotides on mosquito gorging and the development of the microfilariae from the jird peritoneal cavity and from the dog venous blood in Aedes aegypti. As a phagostimulant 10^-3M ATP is the most effective of the nucleotides tested. The microfilariae from the jird peritoneal cavity have been proved to reach stage III (i.e. infective stage) as those from the dog, although the rate is lower in the former. It is also proved that the microfilariae develop to infective larvae in the mosquitoes which have not taken blood, serum or protein meals.

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Infectivity titrations were performed for each of the 4 prototypes of dengue (DEN) viruses by focus counting on BHK21 cells (FFU), by plaque formation on LLC-MK₂ cells (PFU), and by intracerebral inoculation into suckling mice (LD₅₀) The FFU titers were almost similar as LD₅₀ for all the 4 types of DEN and these titers were also similar to PFU except type 2 DEN (DEN-2), which showed lower PFU than FFU or LD₅₀. Neutralization (N) tests were performed for standard anti-DEN sera by 50 per cent focus reduction (FR50) and by 50 per cent plaque reduction (PR50) methods. Both values were almost the same except anti-DEN-2, whcih showed higher PR₅₀ than FR_50. The principle of these methods were also applied to Japanese encephalitis and chikungunya viruses. Hemagglutination-inhibition (HI) and FR₅₀-N tests on several human sera indicated that FR₅₀ is more specific and sensitive than HI to detect typespecific antibodies.

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Twelve established cell lines including 7 mouse-derived cell lines and primary chick cmbryo fibroblast cells were examined for their susceptibility to rabies virus. The results indicated that, in addition to CER cells and BHK-21 cells, murine neuroblastoma cells and human neuroblastoma cells (SYM cells) are highly permissive to infection with both fixed and field rabies strains and suggested the usefulness of these neuronal cell lines in various immunologic aspects of rabies studies in which histocompatibility requirements play a significant role.

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