McLeiod—The Walden Inversion—A Critical Review. 511 
action of potassium hydroxide or silver oxide on d bromisova- 
lerianic acid. These results, when carefully considered, seem 
to indicate that there is no inversion of optical activity in any of 
reactions of optically active valin or its corresponding deriva¬ 
tives. Fisher himself is. at a loss in considering these reactions 
for they show that, if there is anything in the idea of a Walden 
inversion, the influence of any reagent, whether normal or ab¬ 
normal, can not be predicted, but must be worked out carefully 
in each individual case. This necessarily means much tedious 
work in establishing the changes taking place with optically 
active substances—as an immediate result it tends to throw some 
doubt on the absolute configuration of the C 3 acids as established 
by Fisher on the basis of several changes, all of which were as¬ 
sumed to be normal. 
Nomenclature Revised according to Neuberg’s Latest Work. 
COOH COOH COOH COOH 
HC-OH < -HCNH 3 ->HCNHj -- > HCJ—OH 
ch 3 oh ch 3 oh ch 3 ch 3 
d glyceric 1 serine d alanine d lactic 
(dextrorot) (natural) (natural) 
Fisher and Jacobs 19 had shown that d serine had a constitution 
corresponding to that of d glycerinic, the structure of which 
had been proved to be similar to that of d tartaric and therefore 
to d glucose by Neuberg and Silbermann. 20 
COOH COOH 
I I 
HCNH g -f HN0 2 -> HC—OH 
I (N 2 0 3 ) I 
CH 3 OH CH 2 OH 
1 serine d glycerinic 
1 serine gives by treatment with nitrous acid the corresponding 
hydroxy-acid, (1 glycerine acid according to Neuberg and Sil¬ 
bermann) or d glycerinic acid according to Neuberg’s latest 
work (where he shows that d glycerinic acid by addition of 
prussic acid etc. gives d tartaric acid). 21 d glycerinic acid has 
the structural formula therefore as given above 
i»Ber. 40, 1057. 
20 Zeit. fur physiol. Ch. 44, 134 [1905]. 
2 1 Bioch. Zeit. 5, 451. 
