PHYSIOLOGY OF THE INVEKTEBRATA. 431 



" The Chilognatha copulate. In Glomcris and Folt/,renu>t, 

 the genital apertures of the two sexes are brought together 

 during copulation ; but in Jnhis, the penes of the male are 

 charged with the spermatic fluid before copulation takes place, 

 and it is by their agency that the female is impregnated. 

 The Chilajwda have not been observed to copulate, indeed the 

 female shows a tendency to destroy the males, as among the 

 Arancina. The male Gcophilus* spins webs, like those of 

 spiders, across the passages which he frequents, and deposits 

 a spermatophore in the centre of each." 



l^he development of the embryo of the Myricvpoda has 

 been worked out by MetschnikofF,t whose papers the reader is 

 referred to for important information. 



The Ixsecta. 



The Lisceta multiply by means of genital organs, and the 

 sexes are distinct. According to M. Lacaze-Dutliiers, | the 

 copulatory organs in these animals present wide and manifold 

 variations. Among the colonies of ants, bees, and wasps, 

 besides the males and females, there are large numbers of 

 neuter individuals. The sexual organs of the Insecta are 

 developed chiefly during the pupal stage ; but the rudiments 

 of these organs exist in the larvas — e.g., the female genital 

 organs exist in the larvfB of Apis, and it is due to an increase 

 in the quantity of nourishment that the larvae become females 

 or queens. 



Among the AjjJtidcc, parthenogenesis occurs ; for many 

 successive generations of females are born viviparously with- 

 out copulation with the males. 



As a typical example of the genital organs in the Insecta, 

 we describe in detail those of Pcriplancta (the cockroach). 

 The male organ consists of numerous short testicular sacs 

 attached to a short vas deferens. It is situated above the 



* Belonging to the ChUopoda. 



t Zeitschrift fiir WissenncJuiftliche Zoolocjte, 1874-5. 



X Annales des /Sciences Xaturelles, tomes 12, 14, 17, 18, and 19. 



