The phylogenetic relationship among toad, frogs and newt from Japan was investigated by means of immunoelecrophoresis. Homologous, heterologous and non-identity reactions between rabbit anti-Bufo bufoantiserum and antigen from each of 13 species and 2 subspecies of Japanese amphibia were examined. The number and positions of arcs appeared in these reactions were compared. The relationship observed in the comparison well coincided with the classification of the upper taxa of amphibia; viz. 1) Hyla arboreais more intimately related toB. bufo, 2) members of Ranidae and Rhacophoridae have equal intimacy forB. bufo, and 3) Cynops pyrrhogasteris most distantly related toB. bufo. By contrasting arcs obtained in non-identity reaction and those obtained in homologous reaction, it was found that toad, B. bufocarried 22 antigens, and among these antigens, one was observed through all amphibians tested, 12 were carried solely by toad, and some of the remainders were common to antigens carried by various frogs. Newts carrid only one antigen common to toad. Based on these results, the phylogeny of Japanese amphibia was discussed.

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Hymenolepis nana (von Siebold, 1852), the dwarf tapeworm causing hymenolepiasis, has been reported to be the common intestinal cestode of rodents and man throughout the world. The authors found spontaneously occurred hymenolepiasis in conventional laboratory hamsters with mass and heavy infections. Some individuals were infected with as many as 188 to 290 worms and in addition, numerous cysticercoids were found in the intestinal villi from the same hamsters. According to the early investigations it is said that there are two ways of infection to rodents. In this study the authors considered a natural autoinf ection is to be the case because cysticercoids and immature worms were abundant in the intestines of hamsters. The infection rate of the hamsters was 15% as 6 hamsters were found infected out of 40. All the cases of the heavily infected hamsters showed loss of weight and some of them died. Particular damage of the intestinal mucosa was not seen by post-mortem examinations, however, chronic inflammation and destruction of intestinal mucosa caused by the worms observed microscopically (the given pictures) . Heavy infection ofHymenolepis nanaoccurred spontaneously in hamsters has rarely been found in Japan. The case reported here seems to be very peculiar one.

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The effect of nasal obstruction on mice-the maice were forced to breathe through the mouthwas studied when the animals were exposed to noxious gases.
It was noted that the forced mouth breathing made the mice less vulnerable to hydrogen sulfide, carbon monoxide and toluen vapor when expressed by the time interval before they lost righting reflex or showed respiratory arrest. The levels of the gases which could induce these sings within 5-10 minutes were significantly elevated with the“mouth breathing”mice.
Possible mechanisms for this phenomenon and its application for men were discussed.

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In the golden hamster (Mesocricetus auratus) the gestation period and the loculus size of the gravid uterus from day 6 to day 15.5 (parturition) of gestation as well as the weight, width (umblicus-back) and lenght (crown-rump) of the embryos from day 9 to the parturition were measured. The results obtained were as follows :
1. The gestation period of the golden hamster was 15 days and 15±3 hours post coitum.
2. The average values of the length (in the direction of uterine long axis) and width (mesometrial-antimesometrial axis) in the loculus of the gravid uterus were 0.39 cm and 0.56 cm at 6 days, and 2.42 cm and 1.74 cm at 15.5 days (parturition), respectively.
3. The average values of the crown-rump measurements, width (umblicus-back) and weight in the hamster embryos were 0.42 cm, 0.24 cm and 0.026 g at 9 days, and 2.40 cm, 1.39 cm and 2.272 g at 15.5 days (parturition), respectively.
4. The loculus size of the gravid uterus, the crown-rump measurements and width (umblicusback) of the embryos in the period from day 13 to day 14 of gestation were markedly increased in comparison with any other period, and the weight increase of the embryos occured rapidly from day 13 of gestation.
5. The shape of the loculus during the gestation was ovoid (mesometrial-antimesometrial axis) until the end of 10 days converged to the spherical form and thereafter changed gradually to the ovoid from in the direction of uterine long axis contraly to the previous days.

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The movement for modernization of experimental animals in Japan started around 1950. Since that time, a quarter of a century has passed. This article outlines the present status of experimental animals in Japan and makes comparisons with various other countries.
Number of animals used : According to three surveys performed in the past (1956, 1960 and 1970), the numbers used of many species are increasing (Table 1) . However, it can not be said simply that the numbers are increasing every year. Taking the United States where surveys are performed every year as an example (Table 3), it is evident that the peaks for use of some species are past (the same tendencies were seen in India and Sweden which have conducted more than four surveys in the past (Table 4) . The same tendencies would probably also be seen in Japan if surveys were conducted annually.
Quality of animals : It is easy to procure genetically and microbiologically controlled rats and mice. However, investigations into the establishment, production and supply of other species of such high quality are insufficient. This situation is almost the same as that in European countries.
Miscellaneous : The present status of other items related to experimental animals is as follow : Facilities and equipment : Higher level facilities were first provided in companies, followed by testing and research institutes. At present, medical universities are providing such facilities.
Feed : Pellet type diets are widely used for the various species.
Care and management : In April, 1974, “The Law for the Protection and Control of Animals”came into force. This law includes regulations concerning animal experimentation but investigations concerning these standards have just begun.
Training of technicians and specialists : The Japan Experimental Animal Research Association provides a correspondence course, tests and recognition for technicians. About 10 veterinary colleges have undergradunte or postgraduate courses for the training of specialists but these are elective except in two or three cases.

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