156 PEOFESSOR E. RAY LANKESTBR. 



evidence of any duct to the coxal gland, either communicating 

 with the exterior or with the alimentary canal or with any 

 blood-space. 



The structure of the coxal gland of Scorpio is shewn in PL 

 VIII_, fig. 7, and in PI. XII, fig. 5. In the first of these figures 

 we have a complete section through the gland as seen under 

 a low power of the microscope. 



We distinguish 



1. The medullary substance, n in PI. VIII, fig. 7. 



2. The cseca of the gland, k. 



3. The inter-csecal spaces lined by extensions of the medullary 

 tissue, o. 



The medullary tissue is a compact variety of the " lacunar 

 tissue " above described (sect. 3). In the central core 

 of medullary substance it is solid with few if any lacunae 

 between the constituent cells, but in the intercaecal passages it 

 opens out so as to leave a wide space bounded and occasionally 

 traversed by a sparsely developed connective tissue (see 

 PI. XII, fig. 5, 0, m). 



The central core of medullary tissue (n PI. VIII, fig. 7) is 

 traversed by a blood vessel cbv, and presumably the contents of 

 this blood vessel are in communication with the lacunar space 

 of the inter-csecal regions of the gland. 



The intercsecal spaces and connective tissue are 

 liable to be misapprehended on first examination. The con- 

 nective tissue is so inconsiderable in amount, its nuclei so 

 small in size, and the " lacunar space " so large, that one is 

 apt to overlook altogether the connective tissue frame-work 

 and to see only the spaces or channels surrounding the 

 glandular caeca. Staining the sections with Borax Carmine, 

 however, suffices to render the connective tissue framework 

 obvious enough, as in PI. XII, fig. 5, m. I have not observed 

 any coagulum nor any free corpuscles in the intercajcal 

 lacunae. 



The caeca of the gland appear in sections as circular or 

 oval spaces lined by a single layer of large cells which con- 

 stitute the special and characteristic epithelium of the coxal 



