BAUMGARTNER: COPULATION IN GRYLLID^. 339 



Another mechanical problem appears in the study of the 

 spermatophore, namely, What causes the sperm fluid to flow 

 out of the ampulla? Are they forced by contraction of the 

 walls, or is there some substance that swells and forces them 

 out? Does air penetrate the wall in some way and thus prevent 

 a vacuum? 



I do not believe that there is any contraction ; at least not 

 much. The walls do not collapse. Farther than this I could 

 find nothing that would throw any light on the problem. 



Differences Found in the Domestic Cricket. 



Lespes describes the spermatophore and the spermatophore- 

 forming organ of this species, but says that he has not seen the 

 act of copulation. I can readily believe the latter statement, 

 as the insects are much more shy and will not mate readily 

 when watched. Nevertheless I witnessed the process several 

 times. The behavior during courting and the movements dur- 

 ing the transfer of the spermatophore are very similar to 

 those of the field crickets. The differences are of no conse- 

 quence. 



The spermatophore is lighter in color, as Lespes says. But 

 this is in accord with the general lack of color in this species. 

 It is a little shorter and stouter, as the Frenchman indicated. 

 The plate is also narrower and more bent. But the cavity does 

 not extend back into the papilla, as I have already explained 

 about our field crickets. 



There is one point to which I should like to call attention. 

 Lespes does not speak of it, yet shows a difference in the draw- 

 ings. In the house cricket the thread is a direct continuation 

 of the canal. This is correct for this species, and is precisely 

 what I find in our field cricket. I have not seen the spermato- 

 phore in G. campestHs; but judging from our domestic and field 

 crickets, and the conditions I find in Nemobius, I do not be- 

 lieve that Lespes is correct when he indicates a break between 

 the thread and the plate, as he shows in his drawings, figure 2. 

 The canal could not be continuous if his drawing is correct. But 

 Lespes thought that the thread was the mass of sperm, and 

 so not thinking of the thread as a hollow conducting tube he 

 might have a break in it. 



The mold differs from that of our field cricket about as it 

 differs from Gryllus campestris, judging from Lespes's descrip- 

 tion. The hooks on the superior plate are rudimentary or 



