CH1TIN IN THE CARTILAGES OF LIMULUS AND SEPIA. 177 
that this is really a nitrogenous body — glycosamine — having 
the formula, C 6 H l3 N0 5 . 
When dissolved in hydrochloric acid the solution of chitin 
is colourless, and chitin can be precipitated from this solution 
unchanged by the addition of water. When 1 the solution is 
boiled it becomes black in consequence of a decomposition, 
which is completed in about an hour. On evaporation impure 
hydrochlorate of glycosamine is obtained, and is purified by 
recrvstallising repeatedly. This body is easily soluble in water, 
soluble with difficulty in alcohol, and reduces alkaline solutions 
of cupric and silver salts. 
Professor Gamgee kindly sent to Professor Lankester 
some crystals of this salt, which he had prepared from 
lobsters. I also prepared some from the exoskeletons of 
cockroaches. 
The naked-eye examination of these crystals showed them to 
belong to the monoclinic system. 2 
The angles were, however, not perfect; the crystals were 
consequently redissolved in water, and allowed to recrystallise 
therefrom on a glass slide. They were then submitted to 
microscopical examination. 
In the case of the salt prepared from cockroaches the follow- 
ing are the results obtained : in the impure state they have a 
light-brownish tinge, which they lose alter recrystallisation. 
Their form is that of flat parallelograms, as in the case of the 
crystals prepared from Sepia, and these are sometimes in clus- 
ters. Measurement of the acute angle of the parallelogram 
gave on the average 39° 25 '. 
The crystals had no action on polarized light. 
In the case of the salt prepared by Professor Gamgee from 
lobsters, redissolved in water, and allowed to recrystallise on a 
fur Physiol. Chem.,’ vol. ii (1878), p. 213, and “ Ueber Glykosamin,” ibid., 
vol. iv (1880), p. 139. 
1 Gamgee, ‘ Physiological Chemistry,’ p. 301. 
2 The crystals which I had the opportunity of examining were about half 
an inch long ; Professor Gamgee states that with plenty of material he can 
obtain crystals several inches in length, and of proportionate width. 
VOL. XXV. NEW SER. 
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