8o FERMENTATION BY MUCORS 



Mention will be made further on respecting the difference 

 between the two processes. 



As already hinted, the presence and accessibility of certain 

 kinds of sugar must be regarded as an indispensable preliminary 

 condition for the occurrence of intramolecular respiration ; and 

 this will be more fully elucidated in subsequent paragraphs. 

 Even under otherwise equal conditions, differences exist among 

 the various fungi in respect of the extent to which intra- 

 molecular respiration may develop, and of the energy with 

 which the resulting liberation of carbon dioxide proceeds, in 

 some species the phenomenon seems almost entirely absent, and 

 in others, e.ij. Rhizopus nigricans, it is very feeble. According to 

 DiAKONOw (I.), Penirillium (jlaurum and Aspergillus iiiijer cease to 

 give off carbon dioxide vei'y soon after tlie exclusion of air has 

 been effected, and they perish within an hour, even when grown 

 in nutrient solutions containing sugar. In this case, as was 

 shown by Pasteur (III.) and Brefeld (XIII.), merely extremely 

 minute traces of alcohol are formed. According to a private 

 communication from Prof. Hansen, Schioenning has failed to 

 confirm the contrary report of Elfving (I.) to the effect that he 

 found considerable amounts (up to 4.2 per cent, by vol.) of alcohol 

 in cultures of the first-named fungus ; consequently this report 

 must undoubtedly be based on error. Apart from the true 

 alcohol-yeasts, in the restricted sense of the term, the producers 

 of the largest (percentage) quantities of alcohol are to be found 

 among the Murorecv. The behaviour of these under the con- 

 ditions inducing intramolecular respiration will be dealt with in 

 the next paragraph. 



We will now tvirn to the difference between intramolecular 

 respiration and alcoholic fermentation, and ask ourselves whether 

 this difference is one of principle or merely of degree. Those 

 who inclined to favour the latter hypothesis were able to advance 

 many circumstances in its favour. The chief products (alcohol 

 and carbon dioxide) and the subsidiary ones (glycerin and 

 succinic acid) are the same in both decomposition processes. The 

 objection raised by the opposite party, namely that the ratio of 

 transposition is different in intramolecular respiration, and that 

 a smaller quantity of alcohol is formed per unit weight of sugar 

 consumed, was disposed of by the discovery of Godlewski and 

 PoLZENiusz (1.), in 1897, to the effect that peas stored out of 

 contact with air produce 1 01 to 103 parts of alcohol to 100 parts of 

 carbon dioxide exhaled, i.e. nearly as much as the 104.5 P®^' cent, 

 that should result from alcoholic fermentation according to Gay- 

 Lussac's equation. Nevertheless, so far as we are able to judge 

 in the present state of our knowledge, there exist two funda- 

 mental differences between the processes in question. One of 

 them has already been mentioned, namely the inception of 

 alcoholic feimentation by yeasts in presence of air ; and the 



