Experimental animals are widely used in research work with various infectious diseases. In order to know the influence of infection upon animals, it is a useful procedure to measure the body weight and the size of internal organs. Although, it should be essential to compare the data with those obtained with normal animals, a reliable data of normal ones are not available as yet.
In this connection, the authors started to establish such a picture with normal mice. Male ddD and CFW of from 1 to 65 days' old bred in the author's laboratory were used.
The results are as follows:
1. The periodical increase of weight of each organ was not similar. Organs of a mouse increased in weight after birth but the curves were different one another.
2. The increase of body weight and that of the weight of internal organs do not necessarily coincide.
3. In spleen, a decrease of weight was noted after certain period of time.
Further studies are being undertaken using otherstrains.

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Studies were made on the blood picture of mice following intraperitoneal injection of pertussis toxin and-vaccine.
Female mice of 4 weeks' old, CF#1 (HIKARI) were used in this experiment.
Pertussis-toxin caused marked leucocytosis on the 1st day, which gradually recovered and the normal picture was resumed in 15 days. Pertussis-vaccine also developed leucocytosis, which was most eminent on the 3rd to 6th day. The leucocytosis caused by toxin as well as vaccine was principally that of neutrophiles. The toxin caused slight erythrocytosis on the 1st day, and moderate anemia on the 9th day. No essential difference between the toxin and the vaccine was demonstrated.

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The epizootic outbreaks of this disease in Japan have been reported by many workers. Recently, latent infection seems to be prevailing among laboratory animals especially mice, which occasionally develop symptoms while in use for experiments causing ambiguous results.
In order to prevent the introduction of salmonella carriers into laboratories, investigation was made on feces of mice to check for Salmonella organisms. The isolation method used was as follows:
A pellet of feces of an individual breeding mouse was introduced into a tube of selenite broth which was incubated for 18 hours when subculture was made on MaConkeys agar plate. After 24 hours of incubation, colonies which appeared likely to be Salmonella were tested by slide agglutination with a combined antiserum for S.enteritidisand S.typhimurium. The colonies giving positive reaction were inoculated on and to Kligler Iron Agar Slants.
By using this method, several breeding mouse colonies were checked and one of them was found to be salmonella positive (S.enteritidis) .
From the excretion of Salmonella organisms in feces as checked occasionally on individual mice and the distribution of the organisms in tissues and organs of a mouse examined post-mortem, it was found that Salmonella negative in a fecal specimen from each individual does not necessarily indicate that it is not a carrier. In fact, about 51 percent of mice, of which no Salmonella organisms had been detected in fecal specimen before sacrifice was shown in post-mortem examination to contain the organisms in tissues or organs.
In conclusion, fecal examination would be of some value in detecting Salmonella positive colonies, however of less value in eliminating Salmonellosis from the individuals of a colony.
Most of the cultures of S.enteritidisisolateded in the present study fermented sucrose.
The fact may indicate that a selective medium containing sucrose will possibly eliminate sucrose-positive Salmonella organisms as were the case in the present study.

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