J 52 Beard, On the Occurrence of Dextro-rotatory Albumins in Organic Nature. 



There are several ways known by which stereochemical questions 

 can be solved. Of these two only need be referred to as connected 

 with the present enquiry. These are 1) examination of the optical 

 rotations of isolated (dead) liquid albumins in the polarimeter, 

 and 2} the "lock and key'' method, that is, the positive or negative 

 action of certain ferments, as employed by Em il Fischer. Regard- 

 ing the first, the isolation of the albumins in a state suitable for 

 the study of optical rotation is beset with great intrinsic difficulties, 

 more especially in dealing with minute micro-organisms. Since all 

 living matter is bound up with, and depends upon, the action of 

 ferments, it is anything but easy so to isolate the albumins that 

 they do not undergo autolysis or self-digestion quickly. The second 

 method, that of the action of ferments, is much simpler in practice, 

 and there only remains for brief discussion the reliability of this 

 method of investigation, the question of how far it is to be con- 

 sidered as being a severely scientific criterion. 



Probably to-day a stereochemist would not admit, that these 

 matters were open to doubt or discussion, but mindful of the 

 circumstance, that these lines are written for readers, of whom 

 many are not conversant with the facts of stereochemistry, it may 

 not be superfluous to adduce reasons. One may read I have 

 myself written it that "a ferment fits the substance upon which 

 it acts 'as a key fits a lock'". This simile, and the foregoing 

 thesis, we owe to the genius of Emil Fischer. The dictum is 

 quoted not infrequently, but, as happens with other classic scientific 

 quotations, at times one may doubt whether the citation was made 

 after a study of the original memoirs. It is an excellent rule to 

 verify one's citations, and that I propose to do in this instance. 



Since it is my contention, that the original words and proofs 

 adduced by Professor Emil Fischer suffice amply to establish 

 the legitimacy of this scientific test by means of ferments, and to 

 make it at least equal in value to the test of the optical rotation 

 in the polarimeter, it may be well worth while to give some account 

 of Fischer's fundamental researches upon the question, and in his 

 own words. This is all the more desirable in that, to my know- 

 ledge, there is at present in the English language no concise 

 account of how Fischer arrived at the simile of "lock and key", 

 on what cogent evidences its truth was based. A search of the 

 chemical literature of the matter under discussion will show, that 

 the main facts and conclusions are contained in three memoirs. 

 Of these two will be found in one immense volume (vol. 27) of 

 the Reports of the German Chemical Society, and the third in the 

 2(5 th volume of the German Journal of Physiological Chemistry. 

 The first paper bears the date 1894, and treats of the behaviour 

 of different sugars towards pure yeasts. From p. 2036 the following 



