waite: antennal glands in homarus americanus. 169 



have a discoidal form, are green in color, and lie against the wall of the 

 stomach (p. 64). 



This early account is nearly correct as far as it goes, hut it deals with 

 only those parts resulting from the ectodermic invagination ; the author 

 failed, moreover, to see the connection with the exterior, which would 

 have shown him the relations of the organ and would have prevented 

 the use of the term " Speicheldriisen " in relation to them. 



The next reference to the embryology of the organ is by Lereboullet 

 ('62), who describes (pp. 760, 761), also in the crayfish, the formation 

 of certain glandular bodies of unknown function at the stage when the 

 stomach grows forward to produce the lateral pouches. These bodies 

 are formed of a simple transparent tube, which in one part of its course 

 is coiled, and is directed toward the base of the corresponding external 

 antenna. The green glandular body also formed by coiling of the same 

 tube is not seen until later. 



It is difficult to reconcile this last statement with the preceding, but 

 it seems to indicate that the author believed that there were two glands 

 of different kinds arising in this region, but not simultaneously. The 

 part first referred to is probably the duct to the exterior. 



A. Dohi-n ('70, pp. 253, 254) describes in the basal segment of the 

 antenna, in the early embryonic stages of Scyllarus arctus, a round cell- 

 mass surrounded by a membrane, and outside this by "einer starken 

 Hypodermisschicht." In Palinurus vulgaris, according to Dohrn, the 

 antennal glands lie in the basal segment of the antenna (p. 261). They 

 are surrounded by the hypodermis, but are free from it. The central 

 part is a cavity in which lie rather close together large free cells, while 

 the wall of the gland is continuous by means of the duct with the ven- 

 tral and inner wall of the base of the antenna. The free cells within the 

 cavity are probably of the same origin as those of the wall, and ultimately 

 all are incorporated into the wall of the gland. I think it probable that 

 the author erred at this point, for the " free cells " are probably of differ- 

 ent origin from the others, i. e. of mesodermic origin, and are the Anlage 

 of the end sac. 



Reichenbach ('77, p. 191) finds that the green glands arise by invagi- 

 nation of the ectoderm at the stage when the maxillipeds begin to appear, 

 but he gives no figures of them. 



Grobben ('80, p. 104) says the antennal glands, as well as the shell 

 glands in Moina, arise from the middle germ layer, but he fails to give 

 arguments, descriptive figures, or authority to warrant this conclusion 

 concerning the antennal glands, or even to say in what species it 



