BRAIN AND NERVES. 277 



This glucose is, as THIERFELDEK has proved, identical with GALAC- 

 TOSE. 



If we put aside the above differences in the composition and 

 certain somewhat differing statements in regard to the qualitative 

 reactions of cerebrin, there are still a few general reactions for all 

 cerebrin preparations which may be employed in their detection. 

 From these lately-described properties it has been claimed that, 

 besides in the brain and nerves, cerebriu occurs in the pus-cells, 

 and in the electric organ of the ray. GEOGHEGAN has also found 

 it in a cancer of the liver. 



Cerebrin, as generally described, is in the dry state a loose, 

 purely while, odorless and tasteless powder. On heating it becomes 

 brown at about 80 C., puffs up, on continuing the heat melts and 

 gradually decomposes. It is insoluble in water, cold alcohol, or 

 ether, also in dilute caustic alkali or baryta-water. It swells in 

 boiling water, forming a pasty mass. It dissolves in boiling alcohol 

 (also ether), but on cooling a flocculent precipitate separates, which 

 on microscopic examination is found to consist of a series of balls 

 or grains. Cerebrin is chiefly characterized by these properties, 

 and by its yielding a reducible substance on boiling with dilute 

 mineral acids. 



The PARCUS'S cerebrin differs from the ordinary in the follow- 

 ing particulars : it is not soluble in boiling ether ; on warming it 

 melts without decomposing (which takes place at 145-160 C.); it 

 gives a light yellow solution with concentrated sulphuric acid, and 

 it swells very little in cold water. 



The HOMocEREBRiN and ENCEPHALIN of PARCUS remain iu the mother 

 liquor after the precipitation of the impure cerebriu from the alcohol. These 

 bodies have a tendency to separate as gelatinous mass. Homocerebrin, which, 

 according to PARCUS, is homologous to cerebrin, is similar to it, but dissolves 

 more easily in warm alcohol and also in^ warm ether. It may also be obtained 

 as extremely fine needles. Encephalin is claimed by PARCUS to be a product 

 of the metamorphosis of cerebriu. In the perfectly pure state it crystallizes 

 in small plates. It swells in warm water, forming a pasty mass. Like the 

 cerebrin and the homocerebin, it yields a reducible substance on boiling with 

 dilute acids. 



GAMGEE'S PSEUDOCEREBRIN, which has thus far not been closely studied, is 

 obtained as a by-product in the recrystallization of protagon. 



The cerebrins are generally prepared according to MULLER'S 

 method. The brain is first stirred with baryta-water until it ap- 

 pears like thin milk, and then it is boiled. The insoluble parts 



