APPENDIX IV 



505 



the corpuscles laden with waste stuff are too large to pass 

 the meshes ; they seem to stick on to the connective tissue 

 fibres and gradually find their way down to the hypodermis, 

 where they either break up or else, after discharging their 

 burdens, return into the blood stream. We are inclined to 

 think the latter to be the correct account, for the connective- 



FIG. 70. Diagram of a section of the neck gland or dorsal organ of Apus, drawn 

 upside down (i.e. as the animal swims) so as the better to illustrate the catching 

 of the laden blood corpuscles in the connective tissue net. in, epithelium of 

 the mid-gut ; c, connective tissue belonging to the longitudinal musculature ; en 

 blood stream from the aorta cephalica ; b, blood corpuscles laden with excretory 

 matter ; cu, cuticle (the small arrow indicates the position of the pore shown in 

 the last figure). The glandular epithelium is shaded dark. 



tissue strands were covered with excretory matter, and the 

 corpuscles near the hypodermis were not nearly so heavily 

 laden as those newly arrived. The hypodermis cells them, 

 selves were very different from those of the ordinary cuticle : 

 they were much larger, with larger nuclei, each nucleus 

 containing two or three nucleoli, whereas the ordinary hypo- 

 dermis cells have but one nucleolus. They also stain badly- 



X 



