Coxal glands of the Arachnids. 



259 



granules; cells 

 47 to 



therefore 

 47d L3I). 



tall columnar cells, containing- basophil 



which appear to have secretorj' functions (photos 



The nephridia of segments six 

 and seven, on legs four and five, 

 have become modified from tj^pe in 

 the sense that the labyrinth is 

 very extensive; its tubules forming 

 complicated twists and turns, but 

 the modified secretory portion of the 

 labyrinth is entirely lost. The 

 vesicle has also disappeared, so that 

 from the collecting tubule, to the 

 exit tubule there is an unbroken 

 stretch of labyrinth with striated 

 cells, as in the scorpions, pedipalps 

 and theraphosid spiders. 



In the modified nephridia of the 

 first three and last three legs on 

 the contrary it is the striated portion 

 of the labyrinth which is entirely 

 missing. The short collecting tubule 

 passes directl}' into a tubule lined 

 with cells resembling those of the 

 modified part of the typical labyrinth; 

 this tubule proceeding straight to 

 the exit tubule without any vesicular 

 enlargement (photo 49 NM). 



The modified nephridium of the 

 second appendage, known as the 

 salivary gland, presents some very 

 remarkable features. The saccule 

 and collecting tubule can readily be 

 found and recognised in photos 48, 

 50, 50 a, 50 b, but the collecting 

 tubule opens into a diverticulum 

 (photo 51 DSL) from a long 

 narrow sac (SL), which extends 



posteriorly almost to the end of the body (diagram F 1), occupying 

 a space in the lateral sinus, dorsal to the segmental nephridia. 

 The sac is almost straight, but shows a tendency towards pouch- 



Diagram E. 



Typical nephridium oi Peripatus. 



The saccule (S) passes into the 

 funnel bearing collecting tubule (CT). 

 The striated part {CL) coils upon 

 itself, and at the bend in close 

 proximity to the collecting tubule, 

 there is a short stretch lined with 

 epithelium of a secretory nature (LM), 

 beyond which the striation begins 

 again, the tubule linally passing to 

 the vesicle and outlet at the base of 

 the appendage. 



