Histomorphological study of the testes reveals that 0.2 mg and 0.4 mg of follicle stimulating hormone (FSH) do not show any marked effect on the spermatogenesis of Puntius ticto except that the production of primary germ cells and primary spermatogonia is slightly stimulated. A dose of 0.6 mg of FSH initiates the formation of primary spermatocytes, and with 0.8 mg the secondary spermatocytes and spermatids appear. With 1.0 mg of FSH the testes attain full maturation. By an administration of a further dose of 0.2 mg of FSH the commencement of oozing is initiated. Each addition of 0.2 mg of FSH from now onwards up to 2.0 mg gradually increases the number of primary germ cells and primary spermatogonia and decreases the number of spermatozoa which reveals uninterrupted oozing of the latter.