waite: antennal glands in homarus amekicanus. 199 



secretion of the glutinous material by which the eggs are fastened to 

 the hairs on the pleopods. Glands of the same general structure are of 

 wide distribution in the integument in Homarus and other Crustacea, as 

 well as in the alimentary tract. Laug ('89-94, p. 338) says that the 

 dermal glands of Crustacea take part in excretion. 



It is still questionable whether the branchial glands are modified 

 tegumental glands, or are segmental and therefore belong to another 

 category. The physiological evidence points strongly to their being 

 nephridial organs, and this is strengthened by the fact that Cuenot 

 ('94, p. 249) has found in the branchial glands chemical products 

 closely resembling those which, according to Marcbal ('92), are found in 

 the antennal glands. In histological structure, too, they resemble closely 

 the endsac of the antennal gland. They possess, however, no duct to the 

 exterior, and Cuenot suggests that the products elaborated in these 

 glands may, without chemical change, be carried by the blood to 

 the antennal glands there to be eliminated. 



Boutchinsky ('95, p. 1G8, Tab. VII. Figs. 163, 164) has described 

 the development by invagination from the ectoderm of certain glands 

 whose ducts lead to the gill chamber. These lie in the gill cavity, 

 commonly in the dorsal wall, and he considers them as belonging in 

 the same series as the branchial glands. But even if these are to be 

 classed with branchial glands, they certainly are not, like the branchial 

 glands, homologous with the endsac of the antennal glands, but rather 

 with its labyrinth. I believe, however, that Boutchinsky has erred in 

 classing these with the branchial glands of Cuenot, Kowalevsky, and 

 Allen, for they seem to me to belong rather to the category of tegumen- 

 tal glands. 



The position of the branchial glands in the axis of the gill, and in 

 close relation to the blood vessels, as described by Cuenot and Allen, 

 leads one to believe them to be mesodermic rather than ectodermic 

 structures, and with this their physiological activities are in harmony. 

 They have no duct as far as known, and there are several of them in a 

 single gill. If in each gill they represent a single segmental organ, 

 this organ must be in a diffuse condition. 



So far as the meagre evidence goes, it shows, in my opinion, that the 

 branchial glands belong to the same category as the antennal and shell 

 glands, but that they represent only the mesodermic parts (endsac) 

 of these. It must, however, be confessed that the evidence for this 

 conclusion is not very satisfactory. A careful examination of the de- 

 velopment of the branchial glands will go far towai'd establishing 



