338 INSECTA. 



the white of the egg, and ultimately, before quitting the nidus of its 

 formation, receives from the granular termination of the ovary its last 

 integument or shell. Thus completed, it passes into the excretory 

 canal (r r) ; and this, meeting the corresponding tube derived from the 

 ovaries of the opposite side, joins it to form the common oviduct (Z), 

 through which the egg is conducted out of the body. 



(884.) But we must now advert to certain appendages connected 

 with the common oviduct. These are of two kinds, the gluten-secretors 

 and the spermaiheca. 



(885.) The gluten-secretors (fig. 169,jpp) are glandular caeca opening 

 into the common egg- canal, and are apparently destined to furnish a 

 glutinous fluid with which the eggs become invested before they are 

 expelled from the body ; and thus they are frequently united into long 

 chains and variously- shaped masses, or else the adhesive varnish thus 

 secreted serves to glue the ova to situations favourable to the develop- 

 ment of the embryo. 



(886.) The other organ, or spermatheca (fig. 169, n o), has a widely 

 different oiSice, being a receptacle provided to receive the seminal secre- 

 tion of the male during copulation : it is always situated upon the upper 

 aspect of the oviduct, into which it opens by a small orifice surrounded 

 by a thickened margin or sphincter embracing the neck of the bag, and 

 so disposed as either to retain the enclosed fluid, or to allow it to escape 

 into the oviduct. That this organ really does receive and retain the 

 seminal liquor is proved by the presence of seminal animalcules in its 

 contents ; but the matter has been placed beyond a doubt by the experi- 

 ment of John Hunter*, who actually succeeded in fecundating the eggs 

 of an unimpregnated female by applying to them a little of the fluid 

 contained in its cavity : but that the reader may comprehend fully the 

 reason of such an arrangement, it is necessary to consider the circum- 

 stances under which insects propagate. 



(887.) In most animals, sexual union may be repeated several times 

 during the life of individuals ; but in insects intercourse between the 

 sexes is permitted to take place once only ; and this solitary congress 

 must suffice for the impregnation of all the ova, however numerous, and 

 however imperfect may be the development of some of them at the time 

 when the embrace occurs. 



(888.) Let us take the Hive-bee as an example : in the females of this 

 insect the ovigerous tubes (fig. 170, a a) are excessively numerous, and 

 the eggs produced in them may amount to between 20,000 and 30,000. 

 These eggs, of course, arrive at maturity in succession, and not all at 

 once ; so that, at the moment when the queen-bee meets her selected 

 mate, perhaps the majority of the ova are not in a sufficiently mature 

 condition to be rendered fertile. Nevertheless the meeting of the sexes 

 cannot be repeated; for no sooner has copulation taken place than 

 * Home's Lectures on Comp. Anat. vol. iii. p. 370. 



