48 MANUAL OF HISTOLOGY. 



spleen and tissue of the pancreas, as also in the digest of albumen in 

 pancreatic juice. 



The physiological significance of tyrosin is probably in general allied to 

 that of leucin. 



33. 

 Glycin, C 2 H 3 (NH 2 )0 2 . 



Gtycin or glycocott, or also glut in sugar, which is in reality amido-acetic 

 acid, has not as yet been met with free in the system. It appears, how- 

 ever, on the splitting up of several animal acids, as hippuric and uric, and 

 one of the biliary acids, namely glycocholic. It is also of interest as an 

 artificial decomposition product of glutin and chondrin. It is obtained 

 in greatest abundance by the decomposition of silk-fibrin (fibroin), in 

 which it is present together with leucin and tyrosin. It may be artificially 

 produced from chloracetic acid by the action of ammonia. 



Glycin crystallizes in colourless rhombic pillars belonging to the mono- 

 klinometric system (fig. 30). These crystals bear a heat of 100 C. with- 

 out losing any water, but at 178 C. they fuse, and are decomposed. 

 Glycin is sweet to the taste, without alkaline reaction, soluble in water, 



but almost insoluble in alcohol and ether. It 

 forms acid salts with acids, and can combine 

 with bases or even salts themselves. There 

 must be some substance nearly related to glycin 

 formed in the body, in all probability from 

 glutinous matters (although at present we are 

 unacquainted with it), which in combination 

 with cholic acid constitutes glycocholic acid, 

 and with benzoic, hippuric acid. This sub- 

 stance then becomes free in the form of glycin 

 upon the absorption of water, and splitting up 

 of the two acids. 



_ Glycin leaves the body partly with hippuric 



Fig. so.-crvstais of tfycin of acid through the kidneys, and is partly reab- 

 different forms. sorbed into the blood as a component of glyco- 



cholic acid as (shown by Bidder and Schmidt) in order to undergo there 

 further alterations with which we are unacquainted. 



SOFT 

 N(CH,) t OH. 



Some years ago a new base known as cholin was met with by Strecker 

 (in but small quantities, however) in the bile of oxen and swine. "We 

 know that by boiling lecithin with baryta water neurin is obtained ( 20), 

 a base of strong alkaline reaction. The identity of this substance with 

 cholin has recently been established in a very interesting way. Neurin is 

 now regarded as hydrated oxide of trimethyl-oxethyl-ammonium (Baeyer). 

 Finally, Wurtz succeeded in producing hydrochlorate of neurin from 

 hydrochlorate of glycol and trimethylamin. 



34. 



rso 3 , o 



This substance, containing as much as 25 '7 per cent, of sulphur, was 



Taurin, C 2 H 7 NS0 3 , or C S H 4 j 



