1908-9.] ON THE ORIGIN OF LIFE ON THE GLOBE. © 433 
In addition to the alkyl radicles there are those of benzene and 
indol as, for example, in tyrosine and tryptophane. These appear to be 
associated with the alkyl radicles but they constitute only a small 
percentage of the total protein molecule. 
The work of Kossel and his pupils was paralleled by that of Emil 
Fischer. The latter devoted his energies to the synthesis of proteins in 
the laboratory and the success which he has achieved so far in his 
efforts has been such as to make it possible to hope that the synthesis 
of protein is a matter now of a few years’ steady experiment and inves- 
tigation. The compounds synthesized contain atom-groups formed of 
the amino-acids and because a majority give one of the reactions pecu- 
liar to peptones he has termed them peptides. The method upon which 
he has proceeded is to allow an acid chloride of a halogen fatty acid to 
act on an amino-acid as indicated in the following equation :— 
mH cl COGl-+ NH, CH. COOH = 
CH, Cl 'CONH. CH, COOH+ HCI. 
The resulting product is then made to react with ammonia thus :— 
GH CuCcO. NH. CH,:COOH+-NH,= 
CH, NE CO, NH’ CH, COOH -HECI. 
The compound produced which is called glycyl-glycin can itself be 
converted into a chlorinated compound and that acting on glycin gives 
a peptide holding three amino-atom-groups :— 
Cho Ni CONT CH, CO.NH CH, COOH. 
The compound formed is diglycylglycin. 
The syntheses of peptides have been effected by Fischer and his 
students in over one hundred cases and the largest number of amino 
acid radicals synthesized in the one nolecule as yet is eighteen with a 
molecular weight of 1213 but this suffices to show that the method 
employed is one by which the synthesis of protein from simpler com- 
pounds is ultimately to be accomplished. That the peptides formed by 
Fischer do, in the main, not differ from peptones in the manner in 
which their atom groups are combined is shown by the fact that trypsin, 
the digestive ferment, breaks a number of them up into the simple 
amino-acids just as this ferment does in the case of the peptones. That 
there is any difference at all between the more complex peptides thus 
formed and the peptones themselves is due to the character as well as 
