100 



Mr. E. K. Lankester. 



[June 15 r 



glands," and this, notwithstanding that he has accurately recognised 

 the absence of any duct connecting them with the alimentary canal. 

 He figures such a duct, but remarks in the text of his memoir, that 

 these apparent ducts are really ligaments. 



He further figures and describes the broad triangular offset from 

 the anterior and inferior margin of the gland which appears to me to 

 be in all probability its true duct,* and gives to this the name of 

 " fleshy pedicle." 



Dufour observed and figured something of the minute structure of 

 the coxal (his " salivary ") gland. He shows that its smooth white 

 surface is marked by winding lines of a labyrinthine arrangement, 

 but erroneously attributes their existence to a coiled tubular 

 structure. 



My own observations on the minute structure of the coxal glands of 

 the Scorpions dissected by me are briefly as follows : the three species 

 agreeing in essentials. Each gland is a sac ; the labyrinthine mark- 

 ings seen on the surface being due to the existence of labyrinthine 

 trabecules which rise up from the inner surface of the sac, and break 

 up its lumen into numerous narrow passages as is the case in the 

 coxal glands of Limulus. An injection of freshly precipitated lead 

 chromate forced into the gland did not escape from it by any duct r 

 but distended the triangular "pedicle," which I consider as probably 

 the duct, though I have as yet failed to find any pore corresponding 

 to it on the outer surface of the coxa or of the sternum. 



Coxal glands taken from freshly killed Scorpions and placed in 

 absolute alcohol, and subsequently stained with picrocarmine or 

 hematoxylin, and cut into sections in the usual manner, showed 

 that the gland is a sac with its wall folded inwards, so as to form 

 numerous trabecule, clothed with a remarkable epithelium. The 

 cells of this epithelium are much larger than those of the coxal 

 glands of Limulus, but agree with them in presenting a differentiation 

 of the cortical substance of the cell. Each cell of the epithelium of 

 the scorpion's coxal gland presents in optical section a complete 

 cortical ring of bright dense-looking substance surrounding a trans- 

 parent protoplasm, in the centre of which is the nucleus. The dense 

 cortical substance of each cell appears to be finely striated ; the strise 

 radiating from the medullary substance towards the surface of the 

 cell. This striated structure recalls to mind the striated structure of 

 the cells of the leech's nephridium, and of the mammalian kidney. 



The trabecula? on which these cells rest are cavernous, being filled 

 with blood. The blood spaces so formed are larger than the spaces 



* June 2Mb, 1882. — I am indebted to the skill of my assistant, Mr. A. GL 

 Bourne, B.Sc, for some complete series of sections through small Scorpions, the 

 study of which has led me to doubt whether these glands have any duct. Their 

 exact nature and function require further investigation, with which I am engaged. 



