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MarineBiological Laboratory is collaborating with JSTOR to digitize, preserve and extend access to Biological Bulletin This content downloaded from 159.178.22.27 on Sun, 26 Jun 2016 12:52:35 UTC All use subject toPreliminary to studies on renal function in the crayfish (Maluf, 1940(Maluf, , 1941b, it is necessary to know how urine is retained in the bladders and how discharged. Nothing has been indicated, until the present, as to how urine is retained. There is, furthermore, no adequate study of the anatomical features surrounding the urinary outlet of decapod Crustacea. As a result of this deficit, investigators of renal function in the crayfish have punctured the membranous operculum at the nephropore prior to collecting urine by suction (Marchal, 1892;Boivin, 1929;Herrmann, 1931;Scholles, 1933;Lienemann, 1938). It is not clear why the opercula were destroyed. From Marchal's diagrams it appears that removal of the opercula would tear the ureters and lead into the haemocoele and that, consequently, the urine would be contaminated with blood. Marchal and Boivin, however, stated that the liquid they collected was limpid, clear, and almost colorless and practically uncontaminated with blood. The chemical analyses of Herrmann, Scholles, and Lienemann show that the concentration of inorganic electrolytes in the liquid collected from the excretory orifices was markedly lower than in the blood. The fact that the distal portion of the bladder contacts the base of the excretory eminences at most of its circumference (Fig. 2, B) apparently explains how the urine collected by the afore-mentioned investigators did not contain an appreciable quantity of blood. The urine aspirated by Picken (1936), by piercing the operculum with a fine hypodermic needle, was doubtless, at times at least, notably contaminated with blood as shown by the strongly positive xanthoproteic reaction and by the large discrepancies, in this respect, with regard to the urine from both kidneys. Thus, in one instance, the urine from the right kidney gave a negative xanthoproteic test while that from the left gave a strong reaction. The writer f.ound that urine collected from Cambarus clarkii by suction from intact nephropores invariably gave a weak xanthoproteic but a negative biuret reaction. 134