896 



APPENDIX. 



Cerebrin is a light, colorless, exceedingly hygroscopic powder, which swells up 

 strongly in water, slowly in the cold, rapidly on heating. When heated to 80 0. 

 it turns brown, and at a somewhat higher temperature melts, bubbles up, and 

 finally burns away. It is insoluble in cold alcohol or ether ; warm alcohol dissolves 

 it easily. Heated with dilute mineral acids, cerebrin yields a sugar-like body, pos- 

 sessing left-handed rotation, but incapable of fermentation. 



Preparation. For this see W. Miiller. l 



[CHARCOT'S CRYSTALS. These crystals [Fig. 235], first discovered by Charcot, 

 have been obtained from the semen, the blood of leukaemics, the expectoration of 



[FiG. 235. 



Charcot's Crystals.] 



asthmatics, and the various tissues, 

 azine, as was supposed. J 



It is not identical with ethylinimme or piper- 



NITROGENOUS METABOLITES. 

 THE UREA GROUP, AMIDES, AND SIMILAR BODIES. 

 Urea. (NH 2 ) 2 CO. 



The chief constituent of normal urine in mammalia and some other animals ; 

 the urine of birds also contains a small amount. Normal blood, serous fluids, 

 lymph, and the liver all contain the same body in traces. It is not found in the 

 muscles as a normal constituent, but may make its appearance there under certain 

 pathological conditions. 



[FIG. 236. 



Urea Crystals separated by slow evaporation from Aqueous Solution. (After Funke.)] 



When pure it crystallizes from a concentrated solution in the form of long, thin, 

 glittering needles. [Fig. 236.] If deposited slowly from dilute solutions, the form 

 is that of four-sided prisms with pyramidal ends ; these are always anhydrous. It 

 possesses a somewhat bitter cooling taste, like saltpetre. It is readily soluble in 

 water and alcohol, the solutions being neutral. In anhydrous ether it is insoluble. 



i Op. cit. 



