CONSTITUTION AND DEVELOPMENT OF TERMITES. 9 



are, as a rule, distinguished by the pigmented eyes and the 

 presence of genital appendices in both sexes. 



The gonads are sexually differentiated, and the vasa deferentia 

 and oviducts are present at the time of birth, but there is no 

 trace of the external genitalia, which do not become evident 

 until the larvae are divisible by the greater or less size of their 

 head. 



The soldiers and workers are of both sexes, as Lespes dis- 

 covered for Termes, and MuUer confirmed for the soldiers of 

 Calotermes. Observations made by means of longitudinal 

 and transverse sections allow of my giving some additional 

 particulars. The gonads are evident in every soldier and 

 worker, and persist in a nearly uniform stage of development, 

 regardless of age ; and all the component parts of the generative 

 apparatus of one or the other sex are invariably present, though 

 of very small size. Both the external and internal genital 

 organs are less reduced in the Calotermite soldier than in the 

 soldier and worker of Termes, and are better developed in 

 these forms of both species than in the larvae at the time when 

 the head is beginning to vary in size. 



The greater part of the abdominal cavity is occupied by the 

 gonads and the alimentary canal (the hinder part of the fore- 

 gut, the chylific ventricle, and intestine). The intestine 

 presents a csecal ampulla, which is sometimes greatly dilated, 

 but is much less so at other times, and may even be contracted. 

 In the first case it occupies a large part of the abdomen, and 

 must undoubtedly exercise an indirect pressure on the genital 

 glands, except during the earliest stages of life. The amplitude 

 of the caecum stands indisputably in an inverse ratio to that of 

 the degree of development of the gonads, and its greater or less 

 size is correlated with the presence or absence of certain 

 parasitic Protozoa. These are fully described in an appendix. 

 They are here mentioned with reference only to the singular 

 fact of their absence in substitute or complementary royal 

 forms, whereas they are present, at least in small numbers, 

 in the perfect insects. 



