. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FACTORS AFFECTING SPERM CYCLE OF THE NEWT 127 tuation of light more advantageous. Whether such control would be more advantageous to fresh water forms is difficult to determine. At any event, the sperm cycle of Triturus viridesccns, a fresh water amphib- ian, apparently is limited by the temperatures of the environment. SUMMARY 1. The observations of Adams (1940) on the normal sperm cycle of Triturus viridesccns were confirmed. An active period of gametogenesis following the spring breeding season results in the formation of
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FACTORS AFFECTING SPERM CYCLE OF THE NEWT 127 tuation of light more advantageous. Whether such control would be more advantageous to fresh water forms is difficult to determine. At any event, the sperm cycle of Triturus viridesccns, a fresh water amphib- ian, apparently is limited by the temperatures of the environment. SUMMARY 1. The observations of Adams (1940) on the normal sperm cycle of Triturus viridesccns were confirmed. An active period of gametogenesis following the spring breeding season results in the formation of mature sperm by September. Mature sperm are discharged in the fall but dur- ing winter the testes are inactive, consisting of spermatogonia, sperm, and evacuated cysts. Sperm discharge recurs in the spring. 2. At all periods of the cycle temperatures below 12° C. prevented spermatogenesis and sperm discharge and caused the degeneration of spermatocytes and spermatids. Temperatures above 12° C. induced spermatocyte formation in winter; 21°-25° C. in winter caused sperm discharge and in summer these temperatures allowed normal spermato- genesis. 3. Variations in light rations (constant light, increasing light, con- stant darkness) did not affect the cycle. Lack of food did not inhibit spermatogenesis. 4. It is concluded that temperature is the principal environmental agent influencing the sperm cycle of Triturus viridcscens. LITERATURE CITED ADAMS, A. E., 1940. Sexual conditions in Triturus viridescens. III. The repro- ductive cycle of the adult aquatic form of both sexes. Am. Jour. Anat., 66: 235-275. ALEXANDER, S. S., AND C. W. BELLERBY, 1935. The effect of captivity upon the reproductive cycle of the South African clawed toad (Xenopus laevis). Jour. Exp. Biol, 12: 306-314. ALEXANDER, S. S., AND C. W. BELLERBY, 1938. Experimental studies on the sexual cycle of the South African clawed toad (Xenopus laevis). I. Jour. Exp. Biol, 15: 74-81. BAKER, J. R., AND R. M. RANSON, 193
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