Retardation of Spermatogenesis and Reduction of Motility of Sperm in Ephestia kühniella Z. (Lepidoptera, Phycitidæ), caused by High Temperature.

Summary.

• 1
  There is evidence of only one cycle of spermatogenesis in Ephestia kuhniella Z.
• 2
  Evidence of retardation of spermatogenesis in newly emerged moths reared at high temperatures is seen in the presence in the testes of (a) abundant premetamorphic tubules, and (b) fewer mature sperm-bundles, as compared with those of newly emerged moths reared at room-temperature and with those of seven days old adults reared at 27°C.
• 3
  The smaller size in testes of adults newly emerged reared at room-temperature and those of seven-day-old ones reared at 27°C. is accounted for by the passage of sperm-bundles into the vas deferens.
• 4
  The spermatozoa obtained by dissection from the bursa copulatrix of a paired female Ephestia kuhniella showed the maximum duration of motility in a salt solution of 0.7 per cent. concentration at 20°C.
• 5
  Brother-sister cultures were reared a t 20°C. and at 30°C., and it was found that the duration of the motility (at 20°C.) of the spermatozoa of the 30°C. culture was less than that of the 20°C. culture. The difference was tested statistically and found to be significant.
• 6
  Peculiar cyst-like bodies have been noticed in the sperm-ball. These seemed to be most abundant in the 30°C. material.
• 7
  Although exact observations were not made it was noticed that in 30°C. culture the moths were smaller, the males produced less sperm, pairing was less readily begun, and was accomplished in a shorter time than in the 20°C. culture.