768 
NATURE 
[J UNE 9, 1923 

unmistakable language Sir Richard’s adhesion to the 
views that have been expressed by practically every 
one experienced in the technical administration of 
collieries, it would serve a most useful purpose at the 
present moment; but in addition it presents, as has 
been indicated, an inside view of one of the most 
complex of the various emergency administrations 
developed by the stress of war conditions, and forms 
a document which no student of industrial economics 
can afford to neglect. H. Louis. 

The Structural Units of the Body. . 
Emil Fischer—Gesammelte Werke. Werausgegeben von 
M. Bergmann. Untersuchungen tiber Aminosduren, 
Polypeptide und Proteine II. (1907-1919). Von 
Emil Fischer. Herausgegeben von M. Bergmann. 
Pp. ix +922. (Berlin: Julius Springer, 1923.) 
245. 2d, 
T the beginning of the twentieth century know- 
ledge of the nitrogenous constituents of the body 
lagged far behind that of the fats and sugars, and the 
information available as to the composition and 
structure of the various forms of protein was of the 
scantiest. Within five years a complete change in 
this respect was effected as the result of the labours of 
Emil Fischer and his pupils—not only were the con- 
stituents of the proteins almost completely identified 
both qualitatively and quantitatively, but also the 
artificial synthesis of most of the individual units was 
effected, and the first steps taken towards their coupling 
together to form polypeptides. 
Fischer’s pioneer work on the amino acids, poly- 
peptides, and proteins commenced just prior to his 
taking possession of the new laboratories in the 
Hessischestrasse, Berlin, about 1899, and during the 
next six years this was his main work: he republished 
his collected papers in 1906. Dr. Bergmann has now 
collected the further publications in this series up to 
1916: they amount to a stately volume of 892 pages. 
During the last few years of his life Fischer worked in 
the main at problems in sugar chemistry, but he always 
spoke of his intention to return to investigations of the 
proteins. 
The papers reprinted in the volume before us fall 
naturally into four classes—the investigation of the 
individual amino acids which form the units from 
which the proteins are built up, the synthesis of poly- 
peptides of ever-increasing structural complexity from 
the amino acids, the investigation of the degradation 
products of protein hydrolysis, and the study of the 
remarkable so-called Walden rearrangement of groups 
attached to asymmetric carbon atoms, which takes 
place during a variety of relatively simple chemical 
NO. 2797, VOL. I11] 


reactions. The value of the collected papers as a work 
of reference is materially enhanced by a carefully 
prepared index. 
Fischer’s work in these fields is in many ways typical 
not only of the man himself but also of the German 
method. The problem was attacked thoroughly, 
methodically, and systematically, with all the re- 
sources of a great and newly-equipped laboratory ; an 
adequate number of trained assistants were available, 
funds were not lacking, and the time of the professor 
himself was not too much occupied by routine and 
administrative work, which could be performed equally 
well by a less gifted individual. Publication was 
prompt, and could be secured without that friction 
with editorial committees which is so destructive of 
enthusiasm. 
In all, nineteen amino acids have been separated as 
products of protein hydrolysis. Glycocoll was isolated 
so far back as 1820 by Braconnot, who obtained 
it from gelatin, together with leucine, which Proust 
had found two years earlier in cheese. Oldest of all 
is cystine, the only protein constituent containing 
sulphur in its molecule, which was discovered in 1810 
by Wollaston. Fischer added proline and oxyproline 
to the list in 1901-2, and discovered the more complex 
diaminotrioxydodecanic acid in 1904. Hopkins and 
Cole isolated tryptophane in 1901. The amino acids 
typify all classes of acids: normal paraffins, aromatic 
analogues and their hydroxy derivatives, dicarboxylic 
acids, heterocyclic pyrrolidine compounds, imidazols, 
indols, and lastly diamino substances. They occur 
in the proteins as optically active forms, and have 
mostly been synthesised in this form. 
Having fully characterised the amino acids, Fischer’s 
next step was to devise methods of coupling them 
together, at first in pairs, to form what he named 
dipeptides, and afterwards in increasing numbers 
until a molecule approximating in complexity to the 
actual protein was obtained. It will be evident that 
the number of possible isomerides of such compounds 
obtained by altering the order in which the various 
amino acids are linked together is very large. Thus 
for an octadecapeptide synthesised by Fischer from 
15 molecules of glycine and 3 molecules of lysine there 
are 816 possible different methods of arrangement. 
Judging from the results of the analysis of the products 
of the partial hydrolysis of the natural proteins, they 
never contain long chains of a single amino acid, but 
are highly complex, each following link in the chain 
being a different acid. In this respect there is a 
resemblance to the fats, the natural compounds being 
in the main mixed glycerides containing several fatty 
acid radicles. As a consequence the number of possible 
isomerides of a product having the structure of casein 

