CHEMICAL BASIS OF THE ANIMAL BODY. 153 



considerable importance. It is always prepared by treating pro- 



t.-ids with boiling mineral acids. 1 



It crystallises in rhombic tetrahedra or octahedra ; is not very 

 soluble in cold, but readily soluble in hut water; insoluble in 

 alcohol and in ether. Its aqueous and acid solutions possess a 

 dextrorotatory power. 



I Asparagin. C 4 H 8 X 2 0,+ H 2 O. [COOH . CH a . CH (NH 2 ). 



<|>M LJ. Amido-succinaraic acid. 



Although asparagin is not found as a constituent of the animal 

 body it is a substance of considerable interest to the physiologist. 

 Not only is it closely related to aspartic acid, into which it may 

 be converted by the action of boiling acids and alkalis, yielding at 

 the same time ammonia, but it undoubtedly plays a most impor- 

 tant part in the constructive proteid metabolism of plants. Further 

 it exists iii not inconsiderable amount in many plant-tissues used 

 as food by man, and is known, like so many of the members of 

 the numerous class of amido-acids to which it belongs (leucin, 

 jlycin, &c.) to give rise to urea when taken into the body of <-ar- 

 nivora, 2 and to uric acid in that of birds. 3 



In plant.- asparagin, like leucin, is found chiefly in those parts 

 which afford a store of reserve material, such as bulbs, tubers, &c., and 

 the cotyledons o f seeds. The amount is however largely im-n-a-ed 

 during germination, and it is therefore present in frequently very 

 large quantities in seedlings, as for instance those of yellow lupins 

 (30 p. c.). The increase in the young growing plant is ni-t probably 

 due chiefly to a formation of asparagin out of tin- decomposition of 

 -proteid-, although some may be formed synthetically. The 

 amount i.- greatest when the seeds are germinated in the dark and the 

 seedling sub.-ei|iient ly grown for -Mine time in .-emi-obsciirity and 

 shielded from the access of carbonic anhydride. 1'nder the> ..... mdi- 

 tions the formation of non-nitrogenous (? carbohydrate) material is 

 simultaneously prevented; and putting the two i\\<-\< together it ap- 

 pears probable that the disappearance of a-paragin in seedlings grown 

 under ordinary conditions is tine to its consumption f,,r the synthetic 

 production of proteids. 4 It is conceivable that the amido-acids and 

 amides may similarly play some part in the synthetic nietaboli-m ..(' 

 animal tissues, though to a presumably much -lighter extent, bearing 

 in mind how in plants constructive im taholi-m preponderates so 

 largely over the destructive.* 



Asparagin crystallises readily in large rhombic pii<m- which 

 tan not very s.'.lnbli- in e>ld. hut n-adily soluble in hut water. 

 and are insoluble in absolute ale. .1ml ami in ether. Its solutions 



H. Kn-ii.l.-r. .f. f prnlt . ('he,,,. (2) IM. III. (1871), 8. 314. 

 v. KiiH-ri-in. Xi f. /.'/ I 

 3 v. Kiii.Tirin. /',i,/. MIL (1-7" 

 Cf Vii,,^. /V, v >"./-;v f I'l'ini*. |-|.. r-'. 150, 174. 

 Lea, Jl. ofPhysiol.'Vol. xi. (1890), p. 258. 



