. Bulletin. Natural history; Natural history. 36 Illinois Natural History Survey Bulletin Vol. 31, Art. 2 a species in which spermatogenesis is continuous although the breeding season of females is restricted to late winter and early, spring. The data in Table 1 and Fig. 1 show that raccoon testes grew at a rather uni- form rate from birth until about 10 months of age (through the February after birth), when the average weight of one testis was grams. The testes of juvenile males showed the most rapid gains in weight between December and February. The average weight of a testis from a juve
. Bulletin. Natural history; Natural history. 36 Illinois Natural History Survey Bulletin Vol. 31, Art. 2 a species in which spermatogenesis is continuous although the breeding season of females is restricted to late winter and early, spring. The data in Table 1 and Fig. 1 show that raccoon testes grew at a rather uni- form rate from birth until about 10 months of age (through the February after birth), when the average weight of one testis was grams. The testes of juvenile males showed the most rapid gains in weight between December and February. The average weight of a testis from a juvenile male in November was only 30 percent of the average weight in February. The sample sizes for February, March, and April were small, but there was an indication that the weights of testes in juveniles declined after February. After April testicular weights of juveniles were included with those of adults because a majority of the juvenile males were sexually active by April. In our experience raccoon testes were nearly always found in the scrotum, even at birth, Stuewer's (19436: 63) statements to the contrary notwithstand- ing. They were more prominent in adults than in juveniles, and most prom- inent in adults during the breeding sea- son. Even in immature animals the testes were rarely withdrawn into the body cavity. In Illinois a majority of the male rac- coons reached sexual maturity as year- lings. Although the presence of sperm in the epididymis does not necessarily indicate sexual potency, it does indicate that an animal is in or approaching the period of sexual activity. No juvenile male had sperm in its epididymis prior to October (Table 1). In October the epididymides of about 9 percent of the juveniles contained sperm; by February this figure had increased to 87 percent. An extrusible penis was another indica- tion of a juvenile's stage of sexual de- - velopment (Sanderson 1961a: 14). Oc- casionally, a male was found with a non- extrusible penis but with sperm in
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