Coxal glands of the Arachnids. 239 



labyrinth tubules comprising by far the largest part of the gland 

 (photos 7, 12). 



The outlet is on the posterior aspect of the base of the third 

 appendage (photos 7, 8) and immediately above the exit tubule {ET) 

 lies the saccule [S) (photos 7, 9) the details of which present much 

 the same appearance as in the scorpion, with its thin walls lined 

 with delicate epithelium, the inhanging glomeruli {GLJR) and central 

 lumen of the saccule {CSL) but the saccule in Tarantula is only 

 very partially enclosed by the labyrinth coils. The collecting tubule 

 (CT) which is short, but more clearly defined than in the scorpion, 

 forms the communicating link between the central lumen of the 

 saccule and the labyrinth with its striated cells (photos 9, 9a, 9b, 9c). 



The labyrinth {CL) starting from the saccule opposite the 

 third appendage forms coils and twists running posteriorly as far 

 as the posterior aspect of the fifth appendage, where it turns a 

 little ventrally and then runs forward, underneath the coils, as a 

 straight tubule to the exit tubule on the third appendage. It may 

 be referred to as the ventral tubule {VTL) of the labyrinth 

 (photos 7, 7a). 



In the coiled part of the labyrinth three divisions may be 

 recognised depending upon the character of the epithelium (photos 7, 

 12). Roughly speaking the anterior division {CLa) lies mainly opposite 

 the third appendage; the middle division (CLm) opposite the fourth 

 appendage, and the posterior division (CLp) opposite the fifth 

 appendage, but the coils of the three divisions overlap each other 

 and there is no abrupt change from one division to the other, such 

 as is found in the change from collecting tubule to labyrinth. 



The cells of the labj'rinth throughout show the striated base, 

 but in the middle division the striated base is surmounted by well 

 defined large columnar cells with slightly basophil cytoplasm, the 

 nuclei lying at the base of the column, immediately upon the striated 

 base (photo 10). 



In the anterior division the nuclei lie, almost bare of cytoplasm, 

 along the free border of the striated portion of the cell, while in 

 the posterior division the cells are for the most part fairly clearly 

 defined and cubical, although in this division there is a good deal 

 of variation and in some places the cytoplasm appears almost worn 

 down to the nuclei. These differences in the three divisions appear 

 to be constant; the middle division with its large basophil cells 



