HARD WICKE ' 5 5 CIE NCE - G O SSI P. 



57 



stone and coarse gravel, not by any means easy to 

 capture. 



The two or three localities in which I have taken 

 it are covered at high tide by about three and a-half 

 to four fathoms of water. How respiration is carried 

 on during the period of submergence, which amounts 

 during average tides to about seven hours out of 

 twelve, and during neap tides to some sixty or 

 seventy consecutive hours, is not easy to determine ; 

 for, from specimens which I have kept in a bottle and 

 carefully observed, ^Epophilus does not, like the 

 aquatic Coleoptera, enclose air either among its hairs 

 or under its rudimentary wings. Dr. Kcehler is of 

 opinion that it must be able to suspend that function 

 entirely during submergence. 



It has but poor natatorial powers, and when put 



THE GREEN GLAND OF ASTACUS 

 FLUVIATILIS. 



By Dr. A. B. Griffiths, F.C.S. (Lond. & Paris). 



THE so-called green glands of the fresh-water 

 crayfish lie in the cavity of the head, below the 

 front part of the cardiac division of the stomach. 

 The openings of these organs are to be found at the 

 base of each antenna. The organ, carefully dissected 

 out of the head of a freshly killed crayfish, is seen to 

 consist of two principal parts : an uppermost one, 

 which is a transparent and delicate sac-like body 

 filled with a clear fluid, and an underlying portion of 

 a green colour, glandular in appearance, containing 

 granular cells. 



Fig. 42. — From a photograph of some of Uric Acid crystals isolated 

 from the secretion of the green glands of several crayfishes, and 

 mounted to form a slide for the microscope. In the above figure 

 the urinary pigments coating some of the crystals are to be seen. 



Fig. 43- — From a slide of Murexide, prepared by the action of nitric 

 acid and ammonia on the uric acid obtained from the secretion of 

 the green gland of Astacus Jluviatilis. 



into a bottle of water seems quite helpless, unless it 

 can get hold of some small stone or loose gravel in 

 the bottom, under which it quickly disappears. 



The figure which I send herewith gives a very 

 good idea of the insect ; but, as I have not a micro- 

 meter, I cannot give the exact enlargement ; it is 



about X 16. 



Joseph Sinel. 



David Place, Jersey. 



The " Surrey Garner," edited by Mr. A. Ramsay, 

 F.G.S., of which No. I has just appeared, com- 

 mences with the mollusca of that lovely county, 

 and also contains the editor's address, on " Surrey 

 Scientific Researches," delivered as the presidential 

 address at the annual meeting of the Lambeth Field 

 Club last June. 



Formerly, as is well known, these green glands were 

 looked upon as the auditory organs of the animal ; 

 but in 1848 Professors Will and Gorup-Besanez (see 

 " Gelehrte Anzeigen d. k. Baierischen Akademie," 

 No. 233, 184S) said that this organ probably con- 

 tained guanin, and from this time it has been con- 

 sidered as a secretory organ. 



Having made a careful study of the secretion of 

 this organ from a chemical and microscopical point 

 of view, this memoir details my work and conclusions 

 arrived at concerning this green gland. 



The secretion of this gland is acid to litmus paper. 

 On treating the secretion obtained from a large 

 number of green glands with hot dilute sodium 

 hydrate solution and then adding hydrochloric acid, 

 a slight flaky precipitate was obtained ; and, on 

 examining these flakes under the microscope, they 



