The Physiology of the Antennal Gland of Carcinus Maenas (l.) v. Some Nitrogenous Constituents in the Blood and Urine

It is now well established that the antennal glands of Crustacea, both marine and fresh water, are concerned with regulation of the ionic composition of body fluids (Robertson, 1957; Shaw, i960; Lockwood, 1962; Potts & Parry, 1964). This activity is considered by some to be the main function of the antennal gland (Webb, 1940; Parry, i960). Because it produces urine and is undoubtedly concerned with ionic regulation, there is a tendency to discuss antennal gland function in terms of the physiology of the vertebrate kidney. The unqualified inference, often expressed in general zoology texts, that the antennal gland carries out all the functions of the vertebrate kidney is unwarranted, since information concerning antennal gland function, other than ionic regulation, is extremely limited. This is particularly so when considering nitrogen excretion by the antennal gland. A urine-producing 'excretory organ' is usually thought of as being concerned with, amongst other things, the elimination of nitrogenous waste products. This function is sometimes ascribed to the antennal gland, despite the fact that there is remarkably little information on this aspect of the physiology of the organ. After a survey of nitrogen excretion by Crustacea and a consideration of analyses of the urine of Maia, Delaunay (1931) concluded that the antennal gland was not concerned with nitrogen excretion and that its importance in this respect has been over-estimated by histo-physiologists. With only a little additional information available, Parry (i960) concluded that the antennal gland was concerned primarily with ionic regulation. Ramsay (1961) was more cautious and considered that because information is so limited, and because little is known of invertebrate biochemistry, the possibility remains that the antennal gland may be concerned with the removal of some excretory products. Because the excretion of nitrogen by Crustacea has been little studied, it is considered worthwhile to offer some data resulting from a study of antennal gland function in Carcinus. Measurements of the contribution of urine nitrogen to total nitrogen excretion by Crustacea have not been made. In this paper, figures obtained from analyses of some nitrogenous components of blood and urine of Carcinus are presented. Using this information, the role of the antennal gland of this animal in general nitrogen excretion can be estimated.