SUBSTANCES INACTIVE THROUGH LOSS OF DISSYMMETRY 35 



turned his attention were not fitted to answer the ques- 

 tion asked. But of tliat Pasteur was unconscious. 

 The second reason, which touched him closely, is that 

 they were contradictory in their responses. The active 

 and inactive aspartates resemble each other very much 

 chemically and sometimes differ entirely from the point 

 of view of crystallography, even to the degree of present- 

 ing absolutel}^ incompatible forms, while the active and 

 inactive malates, very similar also as to their chemical 

 composition, are sometimes indistinguishable in a 

 crystalline state. The active and inactive bimalates of 

 ammonia, for example, have the same crystalline form 

 and the same angles. One is often in danger even of 

 taking one for the other, for it happens that the active 

 bimalate does not have hemihedral facets and corre- 

 sponds exactly in form with the inactive bimalate. 



In other words, all the order and harmony observed in 

 the tartrates disappeared, so that not only was Pasteur 

 obliged to abandon without an answer the question which 

 he had put to himself but he might have asked himself 

 anxiously whether in the tartrates he had not accident- 

 ally fallen upon an exceptional case, devoid of all general 

 bearing. But no! Not once, it seems, did this doubt 

 cross his mind. At least his wTitings show no trace of it. 

 From the contradictions which he had observed he con- 

 cludes with a tranquil assurance that the crystalline 

 form has only a secondary importance, since in the 

 aspartates and the malates it no longer shows the beauti- 

 ful accord with the optical properties which are so 

 striking in the tartrates. He, therefore, deliberately 

 threw overboard the correlation of the crystalline form 

 with the rotary power, which remains the most certain 

 and most constant evidence of molecular dissymmetry. 



Let us pause an instant to observe the successive steps 

 which we have made. Herschel gives us the first idea 



