I thank Dr. Philippe Shubik of Eppley Institute for his constant interest and encouragement and Mrs. Irene Boreisha for her technical assistance. Ten subcutaneous injections of 1 mg urethan per g body weight were administered weekly to Syrian golden hamsters at birth and adult age. Significantly higher numbers of forestomach papillomas developed in animals that began to receive urethan at adulthood than at birth, even though there were similar incidences in animals having this lesion in both age groups.

Burrowing mammals often demonstrate structural and functional characteristics which could be interpreted as aspects of adaptation to the low PO2 and high PCO2 of their environment. Whether these characteristics are acquired by each individual as the result of life in the burrow or are genetic traits established through evolution is not clear. To examine the latter possibility aspects of ventilatory control were studied in newborns and adults of two rodents, the surface dwelling white rat Rattus norvegicus, R and the semifossorial syrian hamster Mesocricetus auratus, H , both born and raised in normoxia. Adult H, but not R, manifested the burrowing preference whenever offered the opportunity. Ventilation VE was similar between the two species both in air and hyperoxia, although H had a deeper and slower pattern.

Adult Syrian hamsters Mesocricetus auratus were inoculated intracerebrally with Borna virus. Neither clinical nor pathological evidence of Borna encephalitis developed in any of the animals for an observation time of up to days post inoculation. Sera from inoculated hamsters did not show complement fixing activity during this time. The brains, however, after a variably long incubation time, contained complement fixing Borna antigen and induced Borna encephalitis when injected into the rabbit. A persistent infection state was obtained in adult hamsters inoculated intracerebrally with Borna virus.

Syrian hamsters are solitary animals and should always be kept with one hamster per cage , yet it seems that pet stores often violate this rule. It is not unusual to see groups of hamsters apparently living in peaceful coexistence at pet stores, but there's a reason you should not do this at home. Most hamsters seen at pet stores are quite young, and even Syrian also known as golden hamsters can be kept together at a young age.