1 94 PHYSIOLOGY OF MICROORGANISMS 



sodium occupy very prominent places; yet the relations of these two 

 elements are sometimes reversed. Calcium and the other constituents 

 are subject to considerable fluctuation. If any inference is to be drawn 

 from this work, it must mean that phosphorus is a very important 

 element, serves an essential role, and is of consequence to protoplasm, 

 probably as a basic constituent. Potassium, sodium, magnesium, and 

 calcium are uniformly constant ingredients, are concerned in nutritional 

 exchanges and may in a limited manner be bound in the structure of the 

 protoplasmic molecule. 



The concentration of the culture-medium and brine solutions are 

 known to influence the amount of ash-content of microorganisms. 

 Cramer,* using a i per cent, sodium carbonate bouillon, a 4 per cent, 

 sodium phosphate bouillon and a 3 per cent, sodium chloride bouillon 

 obtained in the case of Msp. cholera respectively 9.3 per cent., 22.3 

 per cent., and 25. 9 per cent, ash (dry weight). 



Other substances are found present in microbial cells. These should 

 be referred to here although more extensive consideration will be given 

 some of them later. 



Enzymes are found in all microbial cells. They are agents employed 

 in metabolism and in the preparation of food for incorporation in the 

 body of the cell and incidentally produce changes which result in 

 products of fermentation as alcohol. They act very specifically inas- 

 much as a particular enzyme is needed for every substance changed 

 as cane sugar, malt sugar, starch, protein, fat, etc. They cause change 

 apparently without altering their nature. They are influenced by 

 many conditions of temperature, reaction, accumulated products, etc. 

 An organism is capable of secreting or containing within its protoplasm 

 several enzymes, each being produced only when the cell is specifically 

 stimulated. 



Toxins much like enzymes may be found within the cell substance 

 or in the medium in which the microorganism may be growing. They 

 are associated with disease-production and pathogenesis. Their force 

 as a poison (the meaning of the word) is incomparably great. Only a 

 small number of microorganisms are able to produce toxins. 



Vitamines are substances, somewhat intangible, which have been 

 found in some microorganisms and quite generally in food substances. 

 They are seemingly essential to life. Their recognition at the present time 

 is largely by solubility and physiological determination upon animals. 



"Cramer, Arch. f. Hyg , 28, i. 



