THE MANIFESTATIONS OF LIFE 87 



elements so minute that they must inevitably elude 

 detection. It is not known, therefore, whether they 

 are present or not. It is, however, known that it is 

 only in the presence of these elements that the functions 

 of life can be carried on. In the vegetable world this is 

 so fundamental in importance that if a single one of 

 these elements S, P, K, Ca, Mg, and Fe is absent, 

 normal development is impossible. 



It is supposed that the living matter protoplasm 

 is purely protein in character, and consists, like egg- 

 albumin, hemoglobin and other proteins, of some com- 

 bination of C, H, 0, N, and S, and that the additional 

 elements serve as electrolytes by which its functions 

 are carried on. 



When we come to study the materials, out of which 

 protoplasm can be built up, most interesting experi- 

 mental studies in plant life are available. 



Thus Proskauer and Beck found that the tubercle 

 bacillus, one of the bacteria, or lowest forms of vegetable 

 life, can grow well in a mixture consisting of: 



Commercial ammonium carbonate (NH 4 H CO 3 ) . 0.35 

 Primary potassium phosphate (K-jPOg) ........ 0.15 



Magnesium sulphate (MgSO 4 ) ................ 0. 25 



Glycerin (C 3 H 8 O 3 ) ......................... 1.5 



Water (H 2 0) ............................. ad 100. 



Raulin made a most painstaking study of the nutrition 

 of a mould, Aspergillus niger, testing it in every possible 

 way and finally discovering that its maximum growth 

 took place in a solution containing: 



Water ..................... 1500 . 00 grams 



Cane-sugar .................. 70 . 00 grams 



Tartaric acid ............... 4 . 00 grams 



(NH 4 ),PO 4 ................ 0.60 grams 



K,CO 3 ..................... 0.60 grams 



MgCO 3 



(NH 4 ) 2 SO 4 



ZnSO 4 



0.40 grams 

 0.25 grams 

 . 07 grams 

 FeSO 4 ..................... . 07 grams 



K 2 SiO 3 .................... 0.07 grams 



So precise was this work of Raulin, that he found the 

 least variation in any of these ingredients produced a 



