INFLUENCE OF ENVIRONMENT ON SEX 



227 



inhabitants. It seemed advisable to try a controlled experi- 

 ment of removing the males from the colonies, and of examining 

 their gonads after various periods of time. 



Experiment 1 (tables 1 and 2). Carried on in salt water aquaria of 

 Princeton University vivarium. The smaller Crepidulas were re- 

 moved from shells inhabited by hermit crabs and also containing colo- 

 nies of C. plana, and the males were selected from them. The only 

 Crepidulas left in each hermit shell were the two or three large females. 

 Some of the males were then placed on and around the females to 

 serve as controls (table 2) while the rest were allowed to attach them- 

 selves in other shells from which all the Crepidulas had been removed 



TABLE 1 



Specimens removed from large colonies containing female, found to he males, anc 



transferred, two or three together, to hermit shells in which 



ivere no other Crepidulas 



61 ? 



62 



63 



67 

 68 



69 

 73 



74 



75 



79 

 80 

 81 



82 



83 



Shrunken to small strands; 

 spermatogonia ; sperm 



Shrunken to small strands; 

 spermatids; sperm; dis- 

 torted nuclei 



Small; spermatogonia; sper- 

 matids; sperm 



Small strands; inactive 



Small strands; few sperma- 

 togonia and sperm 



Small ; spermatogonia only 



Inactive; type A and B cells 

 in wall; few sperm 



Has considerable lumen, 

 empty except for a few 

 spermatogonia and sperm 



Empty; inactive 



Small; inactive 



Small strands; inactive 



Small strands; inactive 



Preparation for oogonial 



division. 

 Small strands; inactive 



SEMINAL VESICLE 



Full of sperm 

 Full of sperm 



Full of sperm 



Thick wall; empty 

 Thick wall; few sperm 



Not included in sections 

 Small; full of sperm 



Full of sperm; unusually 

 large number of apyrenes 



Reduced to indifferent goni- 



duct 

 Thick wall; empty 

 Thick wall ; empty 

 Reduced in size; a few 



sperm 

 Not included in sections 



Not included in sections 



