Ml ruli lEKMKNTATlu.N.^. 8i 



Kecoiul wjII benmie apiHtrent as tin* iiuH-lianics of the two pLeuo- 

 uiena are exuiuiiu'd and foiiij<urL'»l. As ol>s«.*rveil iti liifjliei- ]>]anti^ 

 aiul Mucijrt'u, inti-jiiiiulfcular if.spimtion is muiouliteilh an intra- 

 cellular process, a inanifestiition of vitality on the jjart of the cell 

 as such, and thfrefuiv insejtarahle fniui the corpus of tin* cell. 

 On the other haiiil such a local limitation cannot he assnnn-ti iu 

 the case of alcoholic fermentation by yeast since it has become 

 known that this phenomenon is not due to the action of the cell 

 ]'er ^•«', but to a contained enzyme that is able to exert its powers 

 outside, ami independent of. the cell in which it originated, and 

 can incite the aforesaid decomposition of supir when placed in a 

 test-tube. Throuf^h the discovery of this new fact, the pheno- 

 menon of alcoholic fermentation by yeast has lost, at one blow, 

 its character as a direct manifestiition of vitiility on the jwirt of 

 the yeast cell, and has been transferred to tlie cjitegory of enzy- 

 matic action. Consequently, those who defend the hypothesis 

 that these two processes are identical in princij>le, and ditler 

 merely in degree, will have to seek for the concomitiint action 

 of a similar enzyme in intnimolecular respiration as well. So 

 long, howevei", as this has not been i)roved we must still uphold 

 the assumption that, on the basis of facts — so far as the.se are 

 known — a di.stinction must be dniwu between the formation of 

 alcohol by intraniolecidar respiration (pna-eeding entirely within 

 the cells themselves) and the alcoholic feruienLition excitetl by a 

 yeast enzyme (which may abso act outside the cells). Xeverthe- 

 le.ss, for the sake of simplicity, we may still continue to speak in 

 the following ]»nragraphs of alcoholic ferment-ition induced by 

 Mu'-iir'n. provided the ilitlerence specitied be borne constiintly 

 in mind. 



.^ 239. -Mucor Fermentations. 



Mail, who discovered that alcohol is foinied by intramolecular 

 respiration in certain species of .!/»/•»//>, di<l not further inve.sti- 

 i^ate the chemico-jthysiological aspect of the question. Further- 

 more, the re.searches of I'.vsTKi K (ill.), the next laboin-er in this 

 field. sulYer from the defect that he did not work with pure 

 cultures, without which here (as elsewhere) no reliable results 

 can be obtsiine*! ; and beside.s, the-^^e experiments were mainly 

 undertaken for the sole purpose of supporting the new theory of 

 fennent.ition. Hence FlTZ (IX.) was r»'ally the first (in 1873) ^ 

 examine the question from the chemical siile, Mwor raretiu^tus 

 being the organi.sm selecteil ftu- the purjHj.se. Then followed U. 

 (i.vvox (V.), who in 1S78 teste<l Mic-ur itpirmsiut and .1/. '•/;<•»«<■//- 

 "/./fs for the possession of the faculty in question. Undeniably 

 pure cidtures, however, were fir.st employtnl l>y E. Ch. Hansen 

 (VIll.), who in 18S7 reported on his experiments with Mwor 

 iiiuct'do, M. rai'euKn'U-!', M. er<rfu,<, and M. >'pinosu!!. His dis- 



VOL. II. ¥ 



