THE STRUCTURE AND ORIGIN OF THE EXCRE- 

 TORY ORGANS OF LIMULUS. 



WILLIAM PATTEN. 



THE coxal gland of Limulus has long been regarded as a 

 ductless gland of uncertain significance, but we are now able to 

 demonstrate that even in the adult crabs the organ is provided 

 with a duct several millimeters in diameter and three or four 

 inches long. 



Its development also has been carefully studied, but the 

 structure described as the developing gland proves to be the 

 developing duct ; the embryonic gland has been heretofore 

 entirely overlooked. 



In the adult the duct is so thin walled that it is not readily 

 seen, and is very difficult to dissect. But it may be readily 

 injected with celloidin or asphalt, so that the mass fills the duct 

 and penetrates the lobes of the gland. 



The coils of the duct may then be dissected out in the usual 

 way, or they may be isolated by dissolving the surrounding tis- 

 sues with caustic potash. When the duct is isolated by either 

 of these methods it is seen to run straight forward along the 

 dorso-lateral margin of the plastron, then back again, and, after 

 many ceilings, open into a large, irregular chamber, or end sac, 

 situated in the middle of the fifth nephric lobe, cccl. The duct 

 arises as a tubular outgrowth of the ventral wall of this sac, 

 which represents a remnant of the fifth coelomic cavity; the 

 distal end of the duct finally unites with a short ectodermic 

 ingrowth, readily distinguished in the adult, which opens at the 

 base of the fifth leg, cc.p. 



The secretions from the gland are collected by gradually 

 widening anastomosing tubules. Each of the four lobes of the 

 gland have many separate openings into the large tubules of 

 the longitudinal stolon, st. ; the large tubules empty into the 

 coelomic space, or end sac, and from these a single nephric duct 

 carries the secretions to the external opening at the base of 

 the fifth leg. 



