Behavioral characteristics of scent marking behavior in the Mongolian gerbil were investigated using the open-field apparatus. The gerbils raised in Japan exhibited a similar behavioral topography of scent marking behavior to those observed in the United States. The incidence and frequency of marking behavior were sexually dimorphic with predominance in males. A midventral sebaceous gland of the male was also larger than that of the female. In male gerbils which has been housed with other males (4 animals per cage), the frequency of marking was differed individually among the cage mates. On the other hand, when two males having similar marking frequency were housed in pairs for one month, one of the two increased the marking frequency compared with the prepairing whereas the other decreased it significantly. The evidence tends to support the notion that scent marking behavior is a species-common response in gerbils and that the behavior correlate to dominance and social ranking.

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The bones of the thoracic and pelvic limbs of Lepus brachyurus brachyurus, Pentalagus furnessi and Oryctolagus cuniculus (strain : JW-NIBS) were investigated morphologically and osteometrically. The results obtained are summarized as follows. 1. The length of long bones in limbs is the largest in Lepus except the distal phalanges, next in JW-NIBS and the smallest in Pentalagus. 2. The breadth of long bones in limbs except the distal phalanges is generally larger in Pentalagus than in Lepus and JW-NIBS, and not significantly different between Lepus and JW-NIBS. 3. The area of articular surface in each limb bone is most extensive in Pentalagus. 4. The distal phalanges of Pentalagus are strong and heavy, the largest in length and the widest in breadth, while those of JW-NIBS are small and light. 5. The distances between the right and left cranial ventral iliac spines, acetabula or ischiatic tuberosities in hip bones are longer in the female than in the male. These differences in sex are distinct in Lepus and JW-NIBS and not clear in Pentalagus.

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Rolling mouse Nagoya (Rolling) was found by Dr. Oda, Univ. of Nagoya, in 1969 as a spontaneous mutant and is characterized by the abnormal gait which appears about 2 weeks after birth. The origin and its mechanism of the motor abnormalities of Rolling has not yet been cleared, but this mouse is now grouped to be one of the cerebellar ataxic mice. The locomotion of the adult mice was automatically recorded and quantitized into the counts of each size of movements, and the gait of Rolling was compared with those of the nonaffected normal mouse, Reeler and Weaver. The reproducibility of the locomotion of the mice was fairly good regardless of the cage used and the observation time (less than 10 min.) . Affected mice showed significantly small number of counts in large size of movements and significantly large number of counts in size of 1/4 and 1/8 (about 6 and 3 cm in practice) of movements due to toppling during gait compared with the nonaffected normal mice. The gait of Rolling was not completely discerned from that of Reeler or Weaver in the spectrum of movements. However, in locus of movements, each mutant showed the specific features of the motor abnormalities. Results presented in this paper suggest that Rolling is similar to Reeler and Weaver with regard to the cerebellar ataxia.

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To examine the influence of sex hormones on the appearance of overt diabetes in NOD mice, oophorectomy and orchiectomy were performed. Castrated males showed a high incidence of diabetes. The time course of onset was similar to that of the intact females. On the other hand, castrated females showed a intact-male pattern of onset with a low incidence. Clinical determinations demonstrated a close similarity between spontaneous and castration-induced diabetes. These data suggest that sex hormones modulate the expression of overt diabetes in NOD mouse, i. e. androgens have at least a suppressive effect.

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An outbreak of canine parvovirus infection in a group of 26 beagles was described. The disease characterized by acute intestinal involvement was highly contagious but fatality was low (1/26) . Transient leukopenie was recorded in some animals. All the convalescent sera were positive in agar gel diffusion test using feline panleukopenia virus antigen. Histopathological examination on fetal dog revealed regressive change associated with formation of amphophilic intranuclear inclusion bodies in the enterocytes of the Lieberkuhn's crypt and regressive change in the lymphoid tissues. Pathologic picture exhibited strikingly resemblance with that of feline panleukopenia.

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A dynamic inhalation apparatus with following characteristics was deviced for experimental infections in small laboratory animals. Nebulized bacterial aerosols were blown against a stainless steel ball of 15 mm diameter which was located at 31 mm distance from the nebulizer and smaller-particle aerosols were wafted up via air stream of 60 liter per minute introducing into an inhalation chamber. Thus 5.7 to 6.7μm particles in average were homogeneously distributed in the chamber and inhaled by animals to their lungs with little individual variations in number of bacteria. The exhausted air was sterilized through HEPA filter after heated at 300°C for 10 seconds, and negative inside pressure of the apparatus produced by the suction system served as a safegurd against aerosol leak.

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An anomaly of the hind limbs has been found in the process of inbreeding of the CFΚ#1 strain. The affected mouse showed a club foot at birth and unusual gait by a dropped foot in the adult. The growth of the affected mouse was slightly delayed in comparison with normal littermates, but reproductive performance was almost normal in both sexes. Anatomical and pathological studies revealed the atrophy of the peroneal muscle group and absence of the common peroneal nerves. The genetical studies showed that this anomaly was mainly controlled by a single autosomal recessive gene. The penetrance and expressivity of the gene was complete in the original or related strains, but incomplete in the other genetic backgrounds. This major gene has been named peroneal muscular atrophy (gene symbol : pma) .

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Emulsions of fresh feces from a conventional mouse, rabbit, dog or cynomolgus monkey were administered orally to germfree and conventional ICR mice. Various fecal floras bearing a striking resemblance in pattern to those in the inoculant became established in the inoculated ex-germfree mice. Reinoculation of these ex-germfree mice with fecal emulsions from a conventional mouse made 21 days after the original inoculation (conventionalization) led to alteration of their floras to the indigenous pattern of conventional mice. The administration of feces from the conventional animals of different species did not appreciably modify the fecal flora of conventional mice. The results indicate that intestinal flora of animals is determined in the first stage by that of the contaminants, but this would be altered later under the predominant influence of the various host factors.

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