AUTHOR S ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, AUGUST 4 



STUDIES ON SEX IN THE HERMAPHRODITE 

 MOLLUSC CREPIDULA PLANA 



III. TEANSFERENCE OF THE MALE-PRODUCING STIMULUS THROUGH 

 SEA-WATER 



HARLEY N. GOULD 



Marine Biological Laboratory, Woods Hole, and School of Medicine, University of 



Pittsburgh 



ONE TEXT FIGURE 



The second paper of this series^ described a number of experi- 

 ments showing the instabiUty of the male phase in the marine 

 gastropod Crepidula plana. In common with other members of 

 the family Calyptraeidae, C. plana passes through a sperm-pro- 

 ducing phase during the early part of its life while it is small 

 (up to about 15 mm. in length) followed by a transitional phase 

 (15 to 20 mm.) and later by an egg-producing phase (20 to 40 

 mm.). Growth goes on with varying degrees of rapidity during 

 life. The functional females are the largest and oldest. The 

 species has a peculiarity in that the development and mainte- 

 nance of the male phase requires a stimulus from the outside, 

 which is furnished by the presence of a larger individual, usually 

 transitional or female, in the immediate vicinity of the potential 

 male. 



The animals are most commonly found in colonies adhering to 

 the inner surface of shells inhabited by hermit crabs. The 

 younger, smaller Crepidulas have various degrees of male devel- 

 opment, those directly attached upon the shells of the large fe- 

 males as a substratum, or close beside them, being nearly all 

 fully developed males, while those at a distance of 5 mm. or 

 over are more likely to have only partially developed male or- 

 gans; the degree of development being less in the specimens far- 

 ther from the source of the stimulus, i.e., the large individuals 

 of the colony. 



» Gould, 1917, II. 



113 



