236 



HARLEY N. GOULD 



TABLE 6— Continued 



GONIDUCT 



Hermit 4 



ondary characters, great numbers of sperm and active spermato- 

 genesis. The results of all experiments indicate that the neuter 

 animal, living in isolation and having reached a considerable 

 size, requires only a very slight stimulus to start the develop- 

 ment of male characters, but a greater one to complete it. 



It is a question whether the production of a limited number of 

 spermatogonia is a sure indication of a stimulus from the out- 

 side; certain specimens which had each been kept isolated in a 

 small vial produced a few spermatogonia; but development 

 never went any farther. 



Experiment 4 was repeated and samples were taken from the 

 colonies at various times. Space is not available to submit the 

 results in tabular form. In general, the neuters quickly took 

 on male characters when placed in colonies with large females; 

 while the neuters kept apart rarely did. Nine days after hav- 

 ing been transferred to the neighborhood of large females, the 

 formerly neuter specimens had testes developed as far as sperma- 

 tids; adult males were found in sixteen days. The specimens 

 had been marked by notches in the shells to obviate any possible 

 mistake in identity. 



When left for long periods, the small Crepidulas living near 

 large females become more and more divergent from those living 



