EXPERIMENT STATION BULLETINS. 371 



SOLUBLE PHOSPHATES FBOM BONE MEAL, 



Milligrams in 250 cc. Average of 10 bacteria. 



Medium. 30 dajs. 60 days. 90 days. 



Asparagin Solution . 

 Peptone Solution. . 

 Beef broth 



In this case, the curves prevent ns from giving a wrong interpreta- 

 tion to the data of the above table. 



Not only chemical products can be analyzed by their curves. The 

 extensive exx)eriments of Kubner (Archiv fuer Hygiene. Bd. 49, p. 355 

 and Bd. 57. p. 193) show that the formation of heat follows the same 

 principle. Eubner measured the temx>erature of fermenting liquids by 

 preventing with greatest care the radiation of heat. Thus the heat ac- 

 cumulated just like a chemical product of fermentation. The tempera- 

 tare curves look sometimes like fermentation curves, sometimes like 

 enzyme curves. This latter type indicates a very large inoculation, so 

 large, that the bacteria did not multiply materially: the constant active 

 mass causes a curve of the enzyme typse. The curves of Kubner on page 

 234 to 241 of vol. 57 of the Archiv fuer Hygiene show the heat pro- 

 duction of B. coli in broth inoculated with 0.4 g.. 2.4 g.. and 5.6 g. of B. 

 coli culture from potato. The first curve is distinctly microbial, the 

 other two are of the enzyme type. Two other series of curves are also 

 of interest, on page 230 and 232 of the same papjer, the one demonstrat- 

 ing the microbial curv^ in the putrefaction of meat juice, urine and 

 excreta of man and animals, the other showing the strictly enzymic 

 curves of the autolysis of liver and muscle. 



It seems tempting to decide by the method of curves whether the 

 spontaneous heating of organic matter in hay stacks, in green com and 

 grain, in tobacco-bales, moist cotton-refuse, etc., is of microbial or purely 

 chemical nature. However, the method fails here, because the 

 chemical and microbial curve in this particular case would be of the 

 same type, Namely, if the heat formation were due to a chemical process, 

 this would produce a higher temperature after a certain time. The 

 higher temperature would increase the rate of the chemical process, 

 and more heat would be produced in the same length of time. This 

 would cause a faster heating, which would result in a still more in- 

 creased velocity, and so on. In short, we have in this case the type of 

 an explosion, where the product accelerates the action. The continu- 

 ously increasing velocity of the process would make it impossible to dis- 

 tinguish between a chemical and a microbial cause of the heat produc- 

 tion. 



It is hardly necessary to mention that the curve of a process will be 

 an absolute means of discussion only in case of pure cultures. In 

 natural fermentations, there is always the possibility that different pro- 

 cesses taking place at the same time destroy the regular form of the 

 curve. A simple example would be the growth of an acid-producing 



