324 ERNEST WARREN. 



clusters of large, swollen hypoclermal cells; these discharge 

 into two chitin-lined oval recesses lying between segment IX 

 and the telescoped sternum of segment X. The secretion in 

 the recesses coagulates and stains very intensely with hajma- 

 toxylin (PI. XX, figs. 79 and 80, gl. c). 



Trichogenic Cells. — Wasmann lays stress on glandular 

 bristles in termitophilous insects. In a typical glandular 

 bristle the ti-ichogenic cell produces the bristle, and around 

 this cell are one or moi'e glandular cells which pour their 

 secretion into the hollow bristle or at the base of the bristle 

 where it perforates the general cuticle. In Termitomimus, 

 TrJigardli figures and describes enormous trichogenic cells 

 passing up into exceedingly minute bristles ; the cells and 

 bristles are entirely disproportionate to each other, and he 

 suggests that these cells may have a secretory function in 

 addition to that of producing the bristle itself. 



In Paracorotoca the trichogenic cells are not very 

 considerably larger than the ordinary hypodermal cells 

 (PI. XYII, fig. 38, tri. c). They contain a globular vacuole and 

 are in direct continuity with the swollen base of the bristle. 

 These trichogenic cells are certainly not actively secreting 

 cells pouring a fluid on the surface of the cuticle ; they 

 have produced the bristle, and their main function has been 

 accomplished. 



As in the case of Termitomimus, the hypodermis in 

 some parts of the body is withdrawn from the cuticle, and 

 in the space there occurs a fluid which is coagulated and 

 granular in the preserved specimen, and this substance stains 

 readily. It would appear that the blood-tissue diffuses 

 through the hypodermis and is thereby altered, and the 

 resulting fluid accumulates between the hypodermis and 

 the cuticle. This fluid presumably passes in some way 

 through the cuticle either in vapour or as a liquid. We have 

 seen that certain kinds of cuticle are probably permeable to 

 this fluid, and where bristles occur there would seem to be 

 ready means of egress around the bases (fig. 38). 



Tracheal System. — No elaborate investio-ation on the 



