19221 



ROSEN — A BACTERIAL DISEASE OF FOXTAIL 375 



Growth was good in all and exceptionally heavy in dex- 

 trose and levulose broth. In every case except glycerin the me- 

 dium was actually rendered more alkaline instead of acid. Does 

 this mean that the foxtail organism does not utilize carbohy- 

 drates? If the production of acid and gas was taken as the only 

 indication of carbohydrate utilization (as some investigators 

 seem to believe) the question would be answered in the negative ; 

 yet in the case of the foxtail organism there is evidence to indi- 

 cate that carbohydrates were used without the production of 

 acid or gas (ammonia production resulted from protein decom- 

 position). It is well known that carbohydrate utilization in com- 

 plex and in simple organisms commonly results in the production 

 of acid and of gas, but it is also known that certain organisms, 

 such as yeasts, decompose carbohydrates and instead of yielding 

 acid they produce alcohol. There are also definite cases on record 

 where carbohydrates are shown to have been used and alkali 

 produced. Thus Miss Karrer (II, '21, p. 78) states: " . . . . 

 the reaction of all the culture solutions with starch as the source 

 of energy was changed during the growth of the fungus (Fusa- 

 rium sp.), this shift being toward increased alkalinity." She 

 presents numerous curves which show the amounts of starch util- 

 ized in nutrient media which were acid at the beginning of the 

 experiment and which developed alkali as growth took place. It 

 is to be noted further that in the nutrient media she employed 

 there was no organic nitrogen. 



It is not intended to go into a lengthy discussion of acid and 

 alkali production in relation to carbohydrates, how carbohydrates 

 in the presence of nitrogenous food may first be utilized and 

 thus exercise a "sparing" action on proteins, or how acid and al- 

 kali may be formed simultaneously, or how a preponderance of 

 alkali may be formed either because of a preferential utilization 

 of acid radicles or because alkali-yielding substances, such as 

 proteins, are utilized to a greater extent. Considerable work has 

 been done on the subject and much remains to be elucidated. 

 Briefly summarized, the following experiments clearly indicate 

 that carbohydrates are utilized by the foxtail organism; first, 

 the marked diastatic action on starch in various media; second, 

 the good growth obtained on media containing nothing but po- 

 tato cylinders; third, the slight growth obtained in aqueous so- 

 lutions containing only 1 per cent of each of these sugars, dex- 

 trose, galactose, mannite. and saccharose; fourth, the increased 



