The present report showed our improved apparatus for rearing germf ree pigs that can be used for experiments for four to five weeks in duration. A transfer isolator of germfree pigs joined to the operating isolator which has been used to procure SPF (specific pathogen free) pigs by hysterectomy by a plastic sleeve (Fig 1, 2) . A pair of isolators that made by Partsco of Columbs, Ohio, prepared for the transfer and rearing of germfree pigs (Fig 3, 4, 5, 6, 7) . The complete operating procedure for sterilizing the isolator units and diet were outlined.
Procurment of baby pigs by the hysterectomy technique was also described. The sow about two days before expected parturition was hoisted by the hind legs, her belly was scrubbed bef or which was anesthetized with carbon dioxide gas. The midline was rapidly incised and the gravid uterus dropped directly into the germicidal trap of the operating isolator. After the pigs are liberated from the uterus they were passed into the rearing units through connecting sleeve. Stillborn pigs have been rare in litters delivered by hysterectomy (Table 1) .

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The authors previously described an isolator apparatus for rearing germf ree pigs and procurement of baby pigs by hysterectomy technique. In this studies, rearing of germf ree pigs in plastic isolators was carried out.
Out of four separate groups of animals (ten pigs), three of these (eigth pigs) were successful from a bacteriological point of view. In one case (two pigs), contamination was occurred with Escherichia coli and streptococci within 3 days of rearing.
As the results, six pigs were reared for one to five weeks without any microbial contamination and no evidence of the illness such as diarrhea was seen during this period, but two pigs died within three days (Table 2) .
The growth rate of the germf ree pigs was comparable to that of SPF (specific pathogen free) pigs of the litter of same Middle Yorkshire. In five weeks of age the both gained 4.6 kg and 4.5 kg with same diet, respectively (Table 3) .
A canned liquid diet for feeding germfree pigs was prepared in Amino Feed Co., Ltd. which con-tained cow's milk, eggs, glucose, liver oil, agar, yeast extracts, vitamins and minerals. The diet was sterilized by steam (Fig. 1) .

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[in Japanese]

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Among 4-to 5-week-old albino rats was noted sporadically a disease characterized by redness and severe oedematous swelling in the extremity of four paws. The hind paws were more frequently affected and tibio-tarsal articulation was most severely affected (Photo 1) . No organisms were detected by culture of exudation of affected articulation, liver, spleen and heart blood on blood agar and PPLO media. However, in the articular lesions innumerable Trypanosomes were observed on smear preparations (Photo 2), and young rats which were inoculated with affected tissue materials subcutaneously in the foot showed a similar lesion associated with a large number of the protozoa. Histopathologic examination revealed purulent arthritis associated with infiltration of polymorphnuclear leucocytes in neighbouring subcutaneous and muscular tissues (Photo 3, 4) . In some joints the formation of granulation tissue was remarkable.

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