A HISTOLOGICAL SURVEY OF GONADAL DEVELOPMENT IN ARION ATER L. (MOLLUSCA, PULMONATA)

A method of breeding the slug Arion ater L. in the laboratorywas established. Measurements were made at monthly intervalsof body weight, weight and volume of the hermaphrodite gland,diameter and number of acini, oocytes and other cell types insidethe acini in field and laboratory-reared animals. Male and femalegametes grow simultaneously in the hermaphrodite gland of fieldanimals during the year. High humidity and low temperature causedinhibition of spermatogenesis and increase in the number offemale gametes in laboratory-reared animals. The average rateof increase in diameter of the oocytes of field samples was10 µm per month and in laboratory samples 9 µm permonth. ^*Present address: Department of Biology, School of Sciences,Ferdowsi University, Mashhad, Iran. (Received 30 September 1977;