160 Decoiiqjosltion of Cellulose 



view of the lack of success witli nutrient dextrose agar and with dextrose 

 mineral salt agar, it was considered desirable to ascertain what position 

 S. cytophaga would assume in this respect. 



The first series of experiments included a ranoe of higher alcohols 

 and carbohydrates some of which have been found useful for general 

 diagnostical work and possess a high nutritive value for bacterial growth. 

 Tests were made in the first instance with two concentrations, viz. 

 O-I and 1-0 per cent. Cultures were made with and without cellulose 

 in order to give (a) inhibitive, and (6) nutritive effects. The results of 

 this series are given in Table V. 



From these, a number of interesting points emerge. Of the fourteen 

 compounds tested, none appears to be capable of meeting the carbon 

 requirements of the organism either in O-l or 1-0 per cent, concen- 

 tration. While unsuitable for growth, they evidently differ greatly 

 in inhibitory power, since decomposition of the cellulose proceeded 

 normally in some, but was completely absent in others. This disparity 

 which, at first sight, might appear to be somewhat inexplicable, permits 

 of an explanation on the basis of the chemical beha^'iour of the various 

 compounds. All those compounds which possess reducing properties, 

 e.g. which induce reduction in Fehling's solution, are shown to exert 

 marked inhibitory effects on the organism. The behaviour towards 

 carbohydrates is, therefore, similar to that previously observed with 

 nitrite, hydrazine and hydroxylamine. Whether this effect is directly 

 connected with an interference of the aerobic requirements of the 

 organisms or of some specific enzymic change must be left open, but 

 it may be mentioned that the contrary effect — stimulation of the 

 anaerobic organisms — has.been observed on the addition of such reducing 

 substances as dextrose, sodium formate, pyrocatechin, sodium hypo- 

 sulphite, etc. to nutrient media^. 



In our experiments saccharose, raffinose, starch, inulin and the 

 higher alcohols are non-toxic even in 1-0 per cent, solution; subsequent 

 tests with gum arable gave the same result. Dextrine is toxic in high, 

 but non-toxic in low, concentrations, while all the rest with the excep- 

 tion of lactose cause inhibition even in 0-1 per cent, strength. Since the 

 two concentrations chosen io\ the experiment were more or less arbitrary, 

 two further tests were carried out. Tlie first consisted in the use of 

 dextrose in the presence of cellulose and indicates that inhibition occurs 

 when the concentration exceeds 0-05 per cent. 



' Kitasato, «. and Weyl, T.. Zeiisch. Hyg. Is!l(l. 8. 41. Bc-ijcrinck. M. W.. Verhaiirl. d. 

 koniiik. Akad. Wclensch. Amsterdam, 1893. 



