On the Intraspecific and Interstrain Variations of the Male Sexual Glands of Schistosoma japonicum

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Abstract
In total, 4064 male S. japonicum were studied. They consisted of individuals from the Chinese, Formosan, Japanese, and Philippine strains, and were obtained from 13 animal host-species. The arrangement of testes can be divided into 2 classes, tandem and non-tandem. The over-all percentage was 47.9 for the tandem group, and 52.1 for the non-tandem. The arrangement was influenced by 2 factors, the host-species, and the strain. The number of testes varied from 1 to 14; 90.5 had 7 testes, and 9.5 other than 7 testes. Although the host-species variations in the number of testes in a strain were not significant, the strain variations were significant among all the strains except between the Chinese and Formosan. Specimens with testis or testes in unusual locations were found, and total 2.5%; the rabbit infected with the Chinese strain gave the highest percentage (9.8), but in the rabbit infected with the Japanese strain the percentage was only 1.5. There is a strain variation in addition to the host-species variation. Six hermaphroditic males were obtained from the animals bisexually infected with the Chinese strain, while none was found in the animals infected with the Formosan, Japanese, or Philippine. Experiments on the guinea pig, hamster, and rabbit, infected unisexually with male cercariae of the Formosan and Japanese strains, did not give hermaphroditic specimens. The number and arrangement of the testes in S. japonicum show great intraspecific variations. There is no indication that the Chinese, Japanese, and Philippine strains, all anthropophilic, are always more closely related with one another than with the zoophilic Formosan strain. Each of the 4 strains of S. japonicum has developed its own characteristics.
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