SUBSTANCES INACTIVE THROUGH LOSS OF DISSYMMETRY 33 



properties, the acid derived from asparagin, that Des- 

 saignes, who had no preconceived idea to put him on 

 his guard, was very excusable for having confused the 

 two. 



This synthetic aspartic acid is especially interesting in 

 that it can be transformed into malic acid by the methods 

 of Piria, and we may well believe that Pasteur was 

 curious to know what malic acid one would obtain with it. 

 Experiment shows that we obtain a malic acid identical 

 with the natural acid, save that it is inactive on polarized 

 light, as are also its salts. This is not all; the field 

 grows more fertile as we cultivate it. The active malic 

 acid of the sorb-tree or of the grape corresponds to one 

 of the active tartaric acids. To what was this new malic 

 acid comparable? To the paratartaric acid inactive by 

 compensation? Pasteur had, against this interpretation, 

 an objection which is no longer valid. "Dessaignes, 

 the father of this malic acid, would," he thought, "in 

 this case have created two molecules endowed with 

 rotary power at the expense of one inactive molecule, 

 but it is impossible to create a single active molecule, to 

 say nothing of two." We know today, not only that 

 the thing is possible, but that it has been realized. 

 It is very probable, if not absolutely demonstrated, 

 that the aspartic acid manufactured by Dessaignes was 

 a combination of the right- and left-handed acids. It 

 is certain that the malic acid which Pasteur had had in 

 his hands was also a paratartaric acid. This error at 

 the outset vitiated the memoir which Pasteur had 

 devoted to comparing the aspartates and malates with 

 each other and with the tartrates. The majority of 

 the deductions which he had drawn from these compari- 

 sons are inexact, and must be abandoned. But there 

 are some which survive and which we should note. 

 Even in the early years of his life as savant, Pasteur 



