waite: antennal glands in homarus americanus. 153 



large central cavity, from which radiate ramifying culs-de-sac. The 

 labyrinth is three times as thick as the saccule and forms the greater 

 bulk of the gland. It is divided by an antero-posterior fissure on the 

 ventral face, so as to be U-shaped, the arms of the U pointing anteriorly. 

 The connection with the overlying saccule is at the end of the lateral 

 arm, that with the excretory duct at the end of the median arm. In 

 the latter case, this is by means of several parallel canaliculi, which open 

 as pores in the wall of the duct. The vesicle is a dorsal outpocketing 

 from the duct, and is not in direct connection with the gland. The 

 labyrinth consists of a spongy tissue formed by the walls of innumerable 

 canals, which anastomose with one another without any determinable 

 system. 



The cells of the saccule are narrow, crowded, with rounded free ends, 

 and without cuticula, while in the labyrinth the cells are markedly 

 striate, and surmounted often by clear vesicles. A cuticuloid covering 

 is sometimes present. 



The present state of opinion as to the function of the antennal glands 

 in Decapoda is not one of complete accord. It needs but a superficial 

 examination of the epithelium in these organs to convince one of their 

 glandular nature. The intra vitam experiments of Kowalevsky ('89) and 

 Cuenot ('94) show conclusively that the cells take up grains of coloring 

 matter introduced into the circulation and eliminate them. Moreover, 

 with the exception of the ductless branchial glands and certain cells of 

 the liver, this function is confined, as far as we at present know, to 

 these antennal glands. The glandular secreting cells of the intestine 

 perform no such function. Conclusions like those of Will und Gorup- 

 Besanez ('48), who asserted the presence of guanin, have been reached 

 by H. Dohrn ('61), 1 by Kirch ('86), and especially by Griffiths ('85). 

 Griffiths got definite tests for uric acid, and he carefully describes the 

 chemical analysis by the murexid method ; further, he obtained small 

 traces of the base guanin. Szigethy ('84) also found what he believed 

 to be uric acid crystals. In each of these cases the analysis was upon 

 the gland in Astacus. 



Marchal ('92, pp. 237-245), on the other hand, made analyses of the 

 excremental fluid of Maia squinado, and could get no traces of urea or 

 uric acid, but did obtain nitrogen. He however obtained an acid some- 

 what analogous to uric acid, which he terms carcinuric acid. This be- 



1 I quote Dohrn and Kirch on the authority of Gerstaecker ('95, p. 1009), as the 

 original papers are inaccessible to me. 



