471 

 2. The external opening of the )*Brick-redu Gland in Limulus polyphemus. 



By R. W. Tower, Physiological Laboratory, Brown University, U. S. A. 



eingeg. 19. August 1895. 



From the first description of the j^Brick-recl« Glands by Packard 

 in 1874 to the present time, many have studied these organs and con- 

 sidered their importance as affecting the position of Limulus among 

 the Arthropods. Some importance too has been placed on a supposed 

 function of these glands as well as on the fact that no efferent ducts 

 or external openings have been found in the adult. 



Each gland consists of a basal portion, lying on either side of the 

 mid-ventral line and extending from the second thoracic appendage 

 to the fifth. From this basal portion and at right angles to it, there 

 arise four large lobes which project one into each of the proximal 

 portions of the second, third, fourth and fifth thoracic appendages. 



Packard^, writing in 1875, was the first to mention and describe 

 the anatomy of these organs, which had entirely escaped the notice of 

 the earlier writers, Van der Hoe ven, Owen and Milne Edwards. 

 He »could not by injection of the gland make out any general open- 

 ing into the cavity of the body or any connection with the hepatic or 

 great collective vein ; any 'attempt to inject the gland from the veins 

 failing«. 



Writing again in 1880 Packard- says that the glands have no 

 outlet, though he finds large active cells Avhich cause him to believe 

 that they are excretory in function. 



E. Ray Lankaster^ in 1884 writes »the minute structure of the 

 glands leave little room for doubt that we have in the coxal glands an 



active secretory apparatus But it must be admitted that no 



abundant or peculiar looking secretion can be detected in this lumen, 

 and further, it seems that there is no outlet for this secretion«. 



Kingsley*, writing later , has likewise been unable in the adult 

 to find any communication between the gland and the exterior ; and 



McMurrich^ in 1894 states that »they have no communication 

 with the exterior in the adult , but in the early stages of development 

 open upon the basal joint of the fifth appendage". 



If the basal portion of the gland is followed posteriorly beyond 

 the junction with the lobe from the fifth appendage, it is found to 



1 American Naturalist. Vol. IX. 1875. p. 5)1 — 514. 



2 Anniv. Mem. of Boston Soc. Nat. Hist. 1880. p. 16—18. 



3 Quart. Journal of Micr. Science. Vol. XXIV (new series), p. 84 & 161. 

 * Quart. Journal of Micr. Science. Oct. 1885. 

 5 Invertebrate Morphology, p. 432. 



27* 



