CHEMICAL BASIS OF THE ANIMAL BODY. 51 



p. 6) have not as yet been prepared in sufficient quantity 1 to admit of 

 the easy and decisive application of the modern methods of organic 

 chemistry to the elucidation of their molecular structure. Work in 

 this direction on a really large scale could scarcely fail to yield 

 important results. Schrotter 2 has recently described the preparation 

 of benzoylated ethers of the albumoses, and intends to apply the 

 method to other proteids and to study the products of decomposition 

 and oxidation of these substances. Whether any real advance will be 

 made in this direction cannot be foretold, but this new departure is of 

 considerable prospective importance. 



No account of the constitution of proteids would be complete 

 without a reference to the views and theories of Pfliiger, and of Low 

 and Bokorny. Pfliiger 3 starting from the characteristic differences 

 between the products obtained by decomposing dead proteids by 

 chemical means out of the body, and the products which arise by the 

 natural decomposition (metabolism) of living proteids (protoplasm) in 

 .the body, has put forward a view as to the difference of living and 

 dead proteid. He considers that in dead proteid the nitrogen exists 

 in the amide form, while in living proteid it is present in the less 

 stable cyanic form. The building-up of living proteid from dead he 

 regards as being carried on by the ether-like union of the isomeric 

 living and dead proteid molecules, accompanied by the elimination of 

 water. During this process the nitrogen of the dead proteid passes 

 into the cyanic condition, and if this is repeated and accompanied by 

 polymerisation the formation of a large and unstable living proteid 

 molecule may be readily accounted for. He further draws attention 

 to the readiness with which polymerisation occurs in the cyanic series 

 and the extraordinarily high molecular energy of cyanogen. Low and 

 Bokorny 4 deal also with the probable mode by which, in the case at least 

 of plant cells, the complex proteid molecule may be built up out of the 

 simpler substances from which these obtain their nitrogen. They 

 consider there is evidence of the existence in living plant cells of some 

 substance of an aldehyde nature. Starting with formic aldehyde, by 

 its union with ammonia the aldehyde of aspartic acid might be 

 obtained, and by polymerisation of the latter in presence of sulphur 

 and with the exit of water a substance with the same composition as 

 an ordinary proteid would arise. Their speculations are ingenious, 



1 But see Chittenden and Hartwell Jl. of Physiol Vol. xi. (1890), p. 435. 



2 Ber. d. deutsch. diem. Gesell. Jahrg. xxn. (1889), S. 1950. 



3 Pfliiger's Arch. Bd. x. (1875), S. 332. 



4 Low and Bokorny's work may be most conveniently quoted by reference to the 

 following volumes of Maly's Jahresbericht d. Thierchem. Bde. x. (1880), S. 3 ; xi. 391, 

 394; xn. 380; xm. 1; xiv. 349, 474; xvi. 8; xvn. (1887), 395. See also Biol. 

 Centralb. Bd. i. (1881), S. 193 ; VHI. (1888), S. 1. 



