1 2 I BRITISH APHIDES. 



The original drawings I here offer the reader are 

 perhaps crude, and are not put forth in competition 

 with the more finished work of others. They may 

 have some interest, however, as being almost exclu- 

 sively camera draioings, and as having been produced 

 under a comparatively small amplification (the twelfth 

 of an inch objective not being often resorted to) ; and 

 particular adroitness in dissection will not be required 

 if their verification be desired. 



The penis is of large relative size in Aphis. It is 

 of a peculiar shape, recurved and enclosed within the 

 cavity of the body, and only exserted during the act 

 of fecundation. A gentle pressure on the abdomen, 

 however, causes the organ to protrude; and when once 

 it has been artificially exserted, it does not appear to 

 return to the body-cavity. It is supported in its 

 action by the embrace of a coriaceous ring and certain 

 plates known as the copulative armature. The act, 

 which requires some time for its completion, is many 

 times repeated ; one male being sufficient for the 

 fecundation of many females. 



Reaumur and De Geer have given ludicrous accounts 

 of the wooing of the males of the great oak Stoma- 

 phis. Lichtenstein, who has witnessed the operation, 

 says, the males are very ardent. 



Perhaps the best method for examining the internal 

 generative apparatus of Aphides is to make a clean cut 

 with sharp scissors across the abdomen; and place the 

 portions in water containing a little syrup or glycerine. 

 Under gradual pressure, or by the aid of needles, a 

 group of tubular vessels, variable in number, come into 

 view. These tubes, having more or less pyriform 

 extremities, are the spermatic capsules, converging 

 at their bases into a fasciculus or bundle, which appears 

 to lie under the intestinal canal of the Aphis. There 

 are two fasciculi present, and they unite into one 

 Bingle canal before passing into the penis. 



These testes seem to float unattached within the 

 liquids of the body-cavity, that is, they are not enclosed 



