COPULATION IN CIMEX 521 



explanation of these appearances can be given at present it is hardly 

 worth while to describe them in further detail. 



To come now to the explanation of the function of this organ, given 

 by Berlese. It has already been indicated that he has described and 

 figured a pair of spermathecae in Cimex lectularius, and it is to be 

 assumed from this and from other points in his account that he be- 

 lieved copulation to take place in the ordinary way, the male organ 

 being introduced into the genital aperture of the female. He states 

 that, in the spermatheca of the right side, which is the larger one 

 of the two, there is a minute pore, through which the sperms can 

 pass out into the abdominal cavity. They then make their way to 

 the organ of Berlese, within which they are destroyed and used up 

 as food material during the period when the female has special need 

 of such for the maturation of the eggs. Some of the sperms pass to 

 the ova and fertilize them in the ordinary manner. The greater part 

 of the sperms received from the male, therefore, are used up by the 

 female as food material, the phenomenon being termed by Berlese 

 ' hypergamesis '. Another and rather different instance 'of the same pro- 

 cess had previously been described by the same author in Scutelleridi. 



Such a state of affairs would be remarkable enough, if that were all, 

 and Berlese's explanation a complete one, but there is strong reason to 



believe that this is far from being the case. The 



. " .... i , r Copulation in Cimex 



strongest evidence against it is the method or copula- 

 tion of the bed bug. Most bugs when copulating attach themselves 

 to one another by their posterior ends, and remain attached for some 

 time; plant bugs may be frequently seen fastened together in this manner. 

 The bed bug, however, does not do this, and nothing suggesting this 

 method of copulation has ever been seen by the senior author in a very 

 large experience of breeding both rotundatus and lectularius. On the 

 other hand, copulation, or what looks extremely like it, is carried on in 

 another fashion quite frequently ; it is usually observed immediately 

 after feeding, but this may, of course, be because it is at that time that 

 bugs kept for experimental purposes are most under observation. The 

 male bug approaches the female from behind, and, with a sudden 

 movement, places his body obliquely across hers, remains in that position 

 for a few seconds, and leaves as rapidly. From the position of the 

 male it is impossible for his penis to reach the genital opening of the 

 female, whereas he is placed precisely as one would expect if his inten- 

 tion were to introduce it into the opening of Berlese's organ, for he is 

 invariably on the right side of the female, and just sufficiently far 

 66 



