The distribution of experimentally administered Pseudomonas aeruginosa was studied in germfree CF#1 mice, barrier-sustained DDD mice with or without oral treatment of aminobenzyl-penicillin and conventional DDD mice. On day 1 after oral administration of 8×10⁷ organisms, more than 10⁸ of organisms/g were recovered from the feces of ex-germf ree mice and the number was maintained during the experiment. On the other hand, from barrier-sustained mice with antibiotic treatment and those without the treatment, 10^4-7 and 10³ organisms were recovered, respectively. In all of monoassociated mice and some antibiotictreated barrier-sustained ones the organisms were recovered also from the lungs, liver, spleen and kidneys. In conventional mice, however, no organisms were recovered from the internal organs throughout the experiment, while some were detectable from the intestinal tracts. The distribution of the organisms in naturally infected mice appears to be similar to that of experimentally infected animals with antibiotics.

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Baby CFA#1 mice were obtained by hysterectomy and reared by hand feeding under aseptic condition. Temperature in the cage was kept at 33°C for first 14 days of age. Artificial milk, diet RM was composed of rat milk (44%) collected from the stomach of killed baby rats, evaporated cow milk (16%) and vitamin mixture (2%) . The diet was homogenized after sterilization and given mice using a latex gum stmach tube at intervals of four hours for 20 to 24 days of age. Feeding size a day (Y ml) was given by the following regression curve, Y=0.412 X - 0.299, (X: body weights in gram) . According to this procedures, 40 out of 74 germfree mice (54%) were weaned with good growth. From a male and a female mice, the germfree CF#1 mouse colony of Takeda was established in 1967 and the lines were distributed to several laboratories of this country.

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Epizootological and clinical observation was made of infectious sialoadenitis ocurring at a rat facility. The disease occurred mostly among animals 8 to 64 weeks of age without specific relevance with sex and age, and clinical signs disappeared within 5 days after the onset. Morbidity rates and duration of epizootics ranged from 13 to 100% and from 5 to 32 days, respectively. Most rats having severe clinical signs of sialoadenitis showed decrease in food uptake, body weight loss and remarkable disorders of estrous cycles.

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A very simple technique for measurement of rat serum corticosterone with radiostereoassay kit using ⁷⁵Se-Cortisol was devised. Only 25-50μl serum was required for this assay. The serum sample were first diluted to 300μl with water and heated in a glass tube to denature the endogeneous Cortisol binding protein. Then an aliquot of the sample was transferred into an assay vial containing ⁷⁵Se-Cortisol, Cortisol binding protein and adsorbent granules. After rotated, an aliquot of the supernatant was taken for counting. High level of rat serum corticosterone was measured with satisfying accuracy by dilution with water. Serum corticosterone levels in 7 normal female Sprague-Dawley rats (7 weeks old, Ca 200g body weight) at 2.00 pm were 29.5 ± 12.2μg/dl (mean± SD) . The levels were lower and higher in rats treated with dexamethasone and with ^1-18ACTH, respectively.

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In total of 17 genetic traits of the 9 strains of rats, Rattus norvegicus, examined, 9 loci showed polymorphic, being a, c, d, h, Es-1, Es-2, Es-3, Amy-1 and sex-influenced esterase (d-allele is not identified [12] . These genetic markers are not only useful as linkage markers but also available for inspection of proper meintenance of inbred rat strains.

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A rapid method is described for the determination of biochemical variants of mice by Titan III cellulose acetate electrophoresis. Variants examined were hemoglobin beta-chain, serum esterase-1, malic enzyme (supernatant form), and isocitrate dehydrogenase (supernatant form) . The present procedure can be recommended as a simplified method to analyze biochemical variants for checking of marker genes in inbred strains of mice.

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Epilepic anormaly strain of mice “E1” derived from National Instiute of Health, Japan were bred by sister-brother mating during the first 3 months and maintained thereafter by random mating at this laboratory. About 20% (21/101) of virgin females and 4 % (2/49) of males were infertile and rate of deliverling was relatively poor ; mean deliverly rate was 70.6%. Deliverly rate were drawn after fourth litter. The mean litter size and weaning rate were 7.54 and 97.9/, respectively. Male E1 mice died following convulsion. Autopsy revealed the obstruction of urether, bleeding in the bladder and seminal vesicules. The time of 50% death was 166 days of age.

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Prothrombin time was measured by a newly developed micro-method using a plastic film available in the market (PARAFILM^®, American Can. Co.) . The comprative study of this micro-method with that of Quick in rats disclosed a good correlation, with correlation coefficient of 0.951, supporting the usefulness of the method for examination of blood coagulability. The new method gave the physiological values of 9.8 sec in rabbits, 12.5 sec in dogs, 13.3 sec in mice, 14.8 sec in cats and 16.0 sec in rats, respectively. Among them, guinea pigs took the longest time of 25.3 sec for the coagulation.

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