12 THEORIES OF FERMENTATION 



his investigations into fermentation were conducted without the aid of the 

 microscope, so that he did not bring to light any actual facts concerning the 

 nature of yeast, but as was 'pointed out, though in vain, by QUEVENNE (I.) as 

 far back as 1838 based his assumptions on hypotheses devoid of foundation. 



In the same way another Frenchman, viz., Desmazieres, the reputed pioneer 

 of the founders of the vitalistic theory of fermentation, cannot permanently retain 

 this title. Like Astier, he is said to have recognised the part played by yeast in 

 fermentation, but, as a reference to his treatise, published in 1826 (in pages 42 

 to 67 of vol. x. of the Ann. des Sc. Nat.\ will show, this assertion is incorrect. 

 In these observations Desmazieres viewed the matter simply as a naturalist. 

 His investigations of the fungoid growths covering the surface of moist substrata 

 were conducted from this point of view, and it was in the course of this study 

 that he examined the mycelia that develop on beer, &c. These consist of masses 

 of elongated cells, to which he gave the name Mycoderma cerevisice. As he 

 fancied they exhibited powers of locomotion, he considered them as belonging to 

 the animal kingdom (animalcida monadina), but, true to his purely descriptive 

 inclinations, he disregarded their physiological properties, and especially their 

 influence on the substratum. Thus the reputation attributed to Desmazieres of 

 having, in 1826, microscopically studied the morphology of the yeast-like cells, to 

 which Persoon had definitely alluded four years earlier, is dissipated by facts. 



On the other hand, a German worker, viz., EKXLEBEK (I.), had already, in 

 1818, correctly estimated the importance of yeast, in that he asserted it to be a 

 living organism, the vital functions of which are the cause of fermentation. 

 Unfortunately he did not follow up this idea, which was thrown out as a mere 

 occasional remark in his treatise on practical analytical experiments. Otherwise 

 he would, in 1818, have anticipated what was only accomplished twenty years 

 later, viz., the establishment of the fact that (alcoholic) fermentation is oausa- 

 tively connected with the life (vita) of certain organisms. This was determined, 

 almost simultaneously, by three investigators working quite independently of 

 each other : Cagniard-Latour in France, and Theodor Sehwann and Friedrich 

 KUtzing in Germany. 



The paths by which these three arrived at their common goal differed. The 

 versatile French technicist is known by name to the majority of educated people 

 on account of the siren he invented, and which is largely used in the science of 

 acoustics. He also devoted some attention to brewing, and compiled a work on 

 the fermentation of beer. The preliminary studies undertaken in this connection 

 led him to more closely investigate the nature of the " yeast," of which notwith- 

 standing the observations of his two compatriots already mentioned practically 

 nothing was then known. This material he examined with the assistance of the 

 microscope, and laid the results of his researches before the Parisian Academy on 

 June 12, 1837, in a short paper (II.) containing the following chief points : 



1. Beer-yeast, instead of being an inanimate chemical substance, as previously 

 supposed, actually consists of small globules which possess reproductive power, 

 and are therefore living organisms. 



2. These bodies appear to belong to the vegetable kingdom, and to reproduce 

 themselves in two ways. 



3. They seem to act upon sugar solution only whilst still living ; wherefore it 

 may, with great probability, be concluded that, by their vital activity, carbon 

 dioxide is liberated, and the sugar solution transformed into an alcoholic liquid. 



13. The Researches of Theodor Schwann. 



As the words printed in italics in the two preceding sentences show, and as 

 a closer examination of the original treatise will more clearly reveal, Cagniard 



