53 



HA RD VVICKE'S SCIENCE- G OS SIP. 



were seen to consist of small crystals in rhombic 

 plates. On treating the secretion with alcohol these 

 rhombic crystals are deposited, which are soluble in 

 boiling water. When these crystals precipitated from 

 the secretion are moistened with dilute nitric acid, 

 alloxanthine (C 8 H 4 N 4 7 ) is produced ; and this body 

 treated with warm ammonia, reddish purple murexide 

 or the ammonium purpurate (C 8 H 4 (NH 4 )N 5 6 ) of 

 Prout is obtained. This murexide so obtained crys- 

 tallises in prisms, which by reflected light exhibit a 

 splendid green metallic lustre, and by transmitted 

 light they are a deep reddish-purple. On running in 

 a solution of potassium hydrate on to a microscopic 

 slide containing some of these murexide crystals, they 

 were dissolved. 



From these. reactions it is evident that these rhom- 

 bic crystals are deposits of uric acid (C 5 H 4 N 4 3 ), 

 from the secretion of the green gland of the crayfish. 

 On examining the uric acid crystals (deposited from 

 the secretion by means of alcohol) by means of the 

 microscope, they are seen to be covered more or 

 less with a very thin and superficial coating of some 

 brown colouring matter, probably some urinary pig- 

 ment. 



But, beyond this discovery of uric acid in the 

 secretion of the green gland of Astacus fluviatilis, 

 I have found that on treating the secretion with 

 boiling hydrochloric acid, a solution was obtained 

 containing in suspension flaky uric acid, which was 

 filtered off; and, on allowing the filtrate to cool, a few 

 crystals of guanin hydrochlorate (C s H 5 N 5 0, HC1, 

 H 2 0) separate which are soluble in hot water ; and 

 on the addition of ammonia to this hot aqueous so- 

 lution, a precipitate is obtained of guanin (C 5 H 3 N 5 0), 

 the precipitated guanin being made up of numbers 

 of minute crystals. On running in warm dilute nitric 

 acid (on to the slide), these crystals disappeared, but 

 were precipitated again on adding a drop of silver 

 nitrate, in the form of the nitrate of silver compound 

 (C 5 H s N 5 0, AgNO,) of guanin. 



I think this investigation proves that this so-called 

 green gland of Astacus fluviatilis is a true urinary 

 organ, its secretion containing uric acid and very small 

 traces of the base guanin. So the green gland is 

 physiologically the kidney of the animal ; the delicate 

 sac-like body is the bladder, and the small duct 

 between them answers morphologically to the ureter 

 of the higher animals. 



In conclusion, I may mention that the crayfishes 

 were obtained from Messrs. Jowett & Co., of Cor- 

 poration Street, Manchester. I wish here to tender 

 my best thanks to Mr. F. J. Deakin (a pupil of mine 

 in the laboratories of the Technical College, Man- 

 chester) for the beautiful photographs he has taken 

 of the microscopic crystals of uric acid and murexide. 



Mimulus luteus. — We have had notification of 

 this plant having been found wild on the banks of 

 the Ribble, near Mytton, by M. E. A. 



GOSSIP ON CURRENT TOPICS. 

 By W. Mattieu Williams, F.R.A.S., F.C.S. 



LOUIS AGASSIZ.— The biography of Agassiz, 

 edited by his widow, and lately published by 

 Macmillan, describes the career of a genuine student: 

 of one who struggled into science in spite of serious 

 difficulties ; who encountered poverty in consequence 

 of his devotion ; who finally overcame all, and by 

 dint of his own moral and intellectual energy rose 

 to a high place among the prophets of Nature. 



One of the days that are written in very bright red 

 letters on the tablets of my memory is that which I 

 spent on the Aar Glacier (August 21, 1S42), where 

 Agassiz and his merry men were encamped on a 

 great boulder in a hut surmounted with a bold in- 

 scription, " Hotel des Neufchatelois." They were 

 studying Nature from her own text-book, in the midst 

 of many hardships, which they heartily enjoyed. 

 The great phenomena of glaciers were then but 

 recently revealed, and some of the most important of 

 the revelations were the work of Agassiz on this spot. 

 No less than ten of us, eight tourists and two guides, 

 started from the Hospice of the Grimsel, and invaded 

 his glacier sanctuary rather rudely and unceremoni- 

 ously (as I now think) ; but he received us most 

 genially and hospitably, supplying coffee and welcome 

 all round. We were chiefly students with one pro- 

 fessor, Pictet— if I understand rightly, the only one of 

 the party previously known to Agassiz. 



The most interesting points of the glacier, the 

 glacier tables, cones, baignoires, trous meridionaux, 

 etc., were visited. We descended a great crevasse to 

 a smoking saloon hewn out of the ice about twenty 

 feet below its surface, and I learned more about 

 glacier details in one day than any amount of reading 

 could supply. 



A little incident displayed the earnest enthusiasm 

 of Agassiz. I had come just fresh from attending 

 Jamieson's class on natural history in the Univer- 

 sity of Edinburgh, the old man having taken up the 

 new and startling doctrine of glacial extension very 

 warmly, in spite of his general conservative tendencies. 

 This had opened my eyes, and, in the course of a 

 walk from Paris to Switzerland, I had made some 

 observations and theories of my own. One of them, 

 which appeared then to be monstrously daring, was 

 that certain mysterious heaps of stones I had seen in 

 the forest of Fontainebleau were moraines of ancient 

 glaciers. I timidly ventured to propound this wild 

 speculation to mine host. He grasped my hand 

 most genially, telling me that he knew them, and 

 was satisfied that I was right, but I must not expect 

 anybody outside of the Hotel des Neufchatelois to 

 agree with me : the time had not yet arrived for belief 

 in die full truth of glacier extension. 



Remembering this and the impression made upon 

 me by the enthusiastic go-ahead temperament of the 



