DERIVATIVES OF AMMONIA AND THEIR COMPOUNDS. 513 



(9. Tunicin is a substance resembling cellulose, and occurs in the integument of 

 the tunicata or ascidians.) 



IV. Division contains the carbohydrates which do not ferment. 



1. Inosit(phaseo-mannit, muscle-sugar) occurs in muscle (Scherer), lung, liver, 

 spleen, kidney, brain of ox, human kidney; pathologically in urine and the fluid 

 of echinococcus. In the vegetable kingdom, in beans (leguminosse), and the juice 

 of the grape. It is an isomer of grape-sugar; optically it is inactive, crystallises 

 in warts with two molecules of water, in long monoclinic crystals ; it has a sweet 

 taste, is insoluble in water, does not give Trommer's reaction, is capable of under- 

 going only the sarcolactic acid fermentation. (Nearly allied are Sorbin from sorbic 

 acid Scyllit from the intestines of the hag-fish and skate and Eukalyn arising 

 from the fermentation of melitose.) 



IV. Derivatives of Ammonia and their Compounds. 



The ammonia derivatives are obtained from the proteids, and are decomposition 

 products of their metabolism. 



(1.) Amines, *.e., compound ammonias which can be obtained from ammonia 

 (NH 3 ), or from ammonium-hydroxide (NH 4 - OH), by replacing one or all the atoms 

 of H by groups of carbohydrates (alcohol radicals). The amine derived from 

 one molecule of ammonia is called monamine. We are only acquainted with 



H v N Methylamine and Tri-Methylamine CHA N, 



CHc 



as decomposition products of cholin (neurin) and of kreatin. Neurin occurs in 

 lecithin in a very complex combination (see Lecithin under Fats, and also p. 36). 



(2.) Amides, i.e., derivatives of acids, which have exchanged the hydroxyl 

 (HO) of the acids for NH 2 . Urea, CO(NH 2 ) 2 , the biamid of C0 2 , is the chief end- 

 product of the metabolism of the nitrogenous constituents of our bodies (see 

 Urine). Carbonic acid containing water = CO(OH) 2 ; in it both OH are replaced 

 by NH 2 -thus we get CO(NH 2 ) 2 , urea. 



(30 Amido-acids, i.e., nitrogenous compounds (p. 341), which show partly the 

 character of an acid and partly that of a weak base, in which the atoms of H of 

 the acid radicle are replaced by NH 2 , or by the substituted ammonia groups. 



() Grlycin (p. 355), (or amido-acetic acid, glycocoll, gelatin-sugar is formed 

 by boiling gelatin with dilute sulphuric acid. It has a sweet taste (gelatin-sugar), 

 behaves as a weak acid, but also unites with acids as an amine-base. It occurs as 

 glycin + benzoic acid = hippuric acid in urine ; and also as glycin + cholalic acid = 

 glyco-cholic acid in bile (p. 355). (6.) LeilCin (p. 341) = amido-caproic acid. 

 (c.) Serin (=? amido-lactic acid) obtained from silk-gelatin, (d.) Asparaginic 

 acid (amido-succinic acid); and (e.) GlutaminiC acid obtained by the splitting 

 up of proteids (p. 342). Other amido-acids are (/.) Cystin = amido-lactic acid in 

 which is replaced by S (see Urine). (g.) Taurin (p. 355), amido-ethyl-sul- 

 phuric acid occurs (except in certain glands) chiefly in combination with cholalic 

 acid, as taurocholic acid in bile. Tyrosin (parahydro-oxyphenyl-amido-propionic 

 acid), an amido-acid of unknown constitution, occurs along with leucin during 

 pancreatic digestion (p. 341), is a decomposition product of proteids, and occurs 

 plentifully in the urine in acute yellow atrophy of the liver. 



To the amido-acids are related (a.) Kreatin in muscle, brain, blood, urine, 

 regarded as methyl-uramido-acetic acid (C4HgN 3 2 ). It has been prepared arti- 

 ficially. When boiled with baryta water, it takes up H 2 0, and splits into urea ; 

 and (6.) Sarkosin (C 3 H 7 N0 2 ), methyl-amido-acetic acid. When boiled with 

 water, heated with strong acids, in the presence of putrefying substances, 

 kreatin gives off water, and is changed into kreatmin (C 4 H 7 N 3 0). This strong 

 base can be rechanged by alkalies into kreatin. 



33 



