QUARTERLY CHRONICLE. 269 



' The deposit in question was composed of a midtitude of 

 snow-white globular masses about the size of a pin's head. 

 Wlien viewed under the microscope, the globules Avere seen 

 to be formed of gi'oups of minute radially disposed needles. 

 They could be easily detached from the scales, and conse- 

 quently afforded a tolerably pure material for chemical ex- 

 amination. They were very diificultly soluble in cold water, 

 insoluble in alcohol and ether, whilst they were readily dis- 

 solved in cold hydrochloric acid and alkalies. From the 

 ammoniacal solution, by evaporation, the characteristic 

 acicular bundles of tyrosin were readily procurable. De- 

 composed by concentrate dnitric acid, they afforded a yellow 

 solution, which on evaporation left a yellow-brown re- 

 siduum, which when moistened with a solution of caustic 

 soda gave a deep reddish-yellow colour, which became 

 brown on evaporation, and finally black (Scherer's test). 



From these and other indications no doubt could be enter- 

 tained that the crystalline material was tyrosin, and further 

 investigation only confirmed this conclusion, and proved the 

 distinction of the deposit in question from xanthoglobulin and 

 leucin. 



Leucin and tyrosin, as is Avell known, occur in many animal 

 organs, even when quite freshly prepared, and the demon- 

 stration by Kiihne, that albuminous matters can be trans- 

 formed into these products by the action of the alkaline 

 pancreatic juice, is extremely interesting. Stadeler and 

 Frerichs have shown their presence also in the lower animals, 

 and especially in the Crustacea, Arachnida, and Insects. But 

 with respect to fish, they were unable to procure leucin and 

 tyrosin from the Ray and from several organs of the Dogfish, 

 although a small quantity of leucin was procurable from the 

 spleen and pancreas, and some tyrosin from the spleen of the 

 latter It is consequently impossible to assign the 

 deposit of tyrosin in the preparations above referred to to 

 any pre-existing in the fish. 



From many considerations it is obvious that in these and 

 in numerous other cases cited the tyrosin is the product of 

 decomposition of the albuminous substances, although it 

 would seem that putrefaction, or an approach to it, is un- 

 necessary to produce the effect, as the author cites an instance 

 of some smoked ham in which the intermuscular substance 

 was studded with innumerable white points, standing in 

 strong contrast with the red flesh, and which had been 

 regarded by the dealer as encysted Trichinae, but on examina- 

 tion by the author proved to be nothing more than minute 

 deposits of tyrosin. 



