CONSTITUTION AND DEVELOPMENT OF TERMITES. 7 



stitute kings respectively. Like the ovaries, the testes increase 

 with the growth in bulk of their possessor, and are therefore 

 notably smaller in a small than in a large king (PI. 19, figs. 

 4, 5). The vesiculse seminales and genital appendices are 

 present, but there is no iutromittent organ. In all these 

 respects the true and substitute kings are identical. 



Both kinds are found to contain ripe spermatozoa, though 

 always few in number, in the vasa deferentia. There is a 

 special liquid which rarely exhibits spermatozoa in the struc- 

 tures which, by analogy with other insects, I call the vesi- 

 culae seminales ; and spermatozoa are always absent in both the 

 vasa deferentia and vesiculae of examples which still possess 

 fully formed wings and of young substitute kings. 



No writer has hitherto observed the spermatozoa, on account 

 of their unusual character and small size ; in describing them 

 I shall limit myself to those features which can be made out 

 without special preparation, as I have not investigated them 

 minutely. 



In order to make sure of their complete maturity, spermatozoa 

 were taken for examination from the spermatheca of the queen 

 (PI. 19, fig. 12). They are relatively short, varying from 12 

 to 20 im in length, non-motile, flattened, and therefore differing 

 in shape according as they are viewed from the face or the 

 side. When seen from the face they are elongate and sub- 

 quadrangular, like a grain of rye, or better, a seed of zinnia ; 

 sideways they appear more or less regularly linear. One ex- 

 tremity usually presents a characteristic thickening, and there 

 are certain cilia-like appendages which are better visible when 

 the spermatozoon is seen sideways. There is no difference 

 between the spermatozoa of the true and those of the substitute 

 king. 



I now pass to Termes lucifugus. In the queen the ovarian 

 tubes are so numerous as to be counted with difficulty, but 

 there are about thirty-six on each side; though they do not ex- 

 ceed half a centimetre in length in the largest individual, their 

 shortness in comparison with those of Calotermes is more than 

 compensated for by their number (PL 18, figs. 1 — 4). They 



