Random-bred Hartley/S guinea pigs originating from National Institute of Health, Japan (NIHJ) and bred in Hamamatsu Farm, Shizuoka Prefecture, have widely been used in this country as a simple designation of Hartley. On the other hand, the same Hartley has long been subjected to inbreeding also in NIHJ under the tentative designation of Hartley-No. 25, and its 20th generation was handed to the Funabashi Farm, Chiba Prefecture, and then the random-bred descendants are being supplied commercially as Hartley/F. In this paper, the Hartley/F and Hartley/S were examined for immune responses to the skin grafts and transfer of sensitized spleen or bone marrow cells. No rejection was seen among individuals of the Hartley/F in any type of transplantation, but each individual of Hartley/S responded immunologically as an allogenic animal in skin grafting and transfer of spleen cells within the strain. Transfusion of bone marrow cells between the Hartley/F and /S revealed that the F possessed common but less histocompatibility genes as compared with the S, as the F rejected the S marrow cells but not vice versa. From the above results, the Hartley/F should be used as an inbred strain being distinguished from the random-bred Hartley/S.

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The selection efficiencies of 6 media for examining microflora of mice were investigated with the organisms isolated from the feces and cecal contents of conventional mice By means of morphological and biochemical tests, of 260 isolates from all types of colonies on DHL agar plates, 254 (97.7%) were identified as Enterobacteriaceae. Also 244 (93.8%) of 260 from typical colonies on SF agar, 153 (85.0%) of 180 from typical colonies on mannitol-salt agar, and 176 (97.8%) of 180 from all colonies on LBS agar, 240 (92.3/) of 260 from all colonies on NBGT-blood agar, and 148 (82.2%) of 180 from typical colonies on potato-dextrose agar were identified as Streptococcus, Staphylococus, Lactobacillus, Bacteroides and yeast, respactively. These results appear to indicate that the organisms of various groups can be distinguished routinely by their colony appearance on the selective media. The constitution of genera and species of organisms may differ even among mice born to the same mother and reared in a same cage, and it was shown to be changeable also in the same animal with different ages as well as different parts of the digestive tract.

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A series of surveys were undertaken on parasites in commercial mice (2, 739 animals in 12 groups), rats (1, 378 animals in 14 groups), guinea pigs (880 animals in 4 groups), rabbits (216 animals in 5 groups) purchased from various sources during the period of January 1969 through February 1972. In terms of their breeding methods those animals were categorized as conventional, SPF-derived conventional and SPF.
The test methods employed were the anus cellophane tape method, floatation with saturated saline and autopsy for internal parasites and direct microscopy for external parasites.
The number of parasite species detected were 4 mites, 6 helminths and 6 protozoae in mice; 3 mites, 1 louse, 6 helminths and 6 protozoae in rats; 1 mite, 2 mallophagas and 1 protozoa in guinea pigs; and 2 helminths and 1 protozoa in rabbits.
External parasites were found in all the conventional groups, but rarely in the conventional SPF-descendant groups and never in the SPF groups. However, internal parasites were found in animals of all the breeding categories. A small fraction of the SPF animals were found to possess oxyuris and protozoae. [Exp. Animals, 23 (1), 15-30, 1974]

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Epizootiological observations were made on natural outbreaks of diarrhea which occurred in infants of mouse colonies of ddY and NIH (gpc) strains. The incidence was higher in NIH than in ddy mice, and was the highest in the first litters decreasing with the seriation of the litter, and disappearing at the third and fifth litters in ddY and NIH mice, respectively. In both strains, onset of the disease was seen at 7 to 13 days of age, and about 63% of affected litters showed diarrhea 8 to 10 days after birth. In usual, the younger the sucklings were at onset, the longer the diarrhea lasted. Large-sized litters were more frequently affected than small-sized ones.

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A remarkable effects of 5, 6-trans-25hydroxycholecalciferol, was shown on the survival rate, growth and skin thickness in ICR suckling mice which were given cadmium nitrate via drinking water.

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