PHYSIOLOGY OF THE INVERTEBRATA. 431 



"The Chilognatha copulate.. In GloTneris and Polyxenus, 

 the genital apertures of the two sexes are brought together 

 during copulation ; but in Jidus, 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 Chilopoda have not been observed to copulate, indeed the 

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

 Araneina. The male Geophilus* spins webs, like those of 

 spiders, across the passages which he frequents, and deposits 

 a spermatophore in the centre of each." 



The development of the embryo of the Myriapoda has 

 been worked out by Metschnikoff,! whose papers the reader is 

 referred to for important information. 



The Insecta. 



The Insecta multiply by means of genital organs, and the 

 sexes are distinct. According to M. Lacaze-Duthiers, J 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 larvae — e.g., the female genital 

 ' organs exist in the larv^ of Apis, and it is due to an increase 

 in the quantity of nourishment that the larvae become females 

 or queens. 



Among the Aphidce, 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 Periplaiuta (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 Chilopoda. 



t Zeitschrift filr WissenscMftliche Zoologie, 1874-5. 



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



