PROTOPLASM 453 



and B. ?iapus, Daucus carota, Solanum tuberosum and Spinacia 

 olereacea.* In lower plants, the bacteria and fungi more 

 especially, it has likewise been shown to be a product of 

 metabolism.f It has been suggested that many of the simpler 

 nitrogenous compounds, as, for example, caffeine, theobromine, 

 the alkaloids, skatol and allied substances such as indoxyl, 

 etc., may be products of protein metabohsm. 



A NOTE ON THE CHEMICAL COMPOSITION OF PROTOPLASM. 



Protoplasm is the living substance of all organisms, and 

 being the centre of metabolic activity it is continually under- 

 going change, wherefore it may not have precisely the same 

 composition from moment to moment. Further, since there 

 are specific, and even individual physiological processes, the 

 protoplasm of different species and of particular plants may 

 not be the same. Any attempt chemically to analyse proto- 

 plasm destroys its vital activity, and therefore the material is 

 no longer protoplasm ; it is true that analysis of the dead 

 protoplasm shows it to contain various elements — carbon, 

 hydrogen, oxygen, nitrogen, phosphorus and sulphur — and 

 that these are combined to form various compHcated structures. 



Thus the analysis of naked masses of protoplasm, the 

 Plasmodia of myxomycetes, for example, gives various results. 

 For instance, Kiesel % found that the plasmodium of Reticularia 

 lycoperdon contained the following percentages of materials 

 estimated on the dry weight : protein, 26-65 ; plastin, 8-42 ; 

 nucleic acid, 3-68 ; nitrogenous extractives, 12-00 ; fat, I7'85 ; 

 lecithin, 4-67 ; cholesterol, 0-58 ; reducing sugar, 2-74 ; 

 non-reducing soluble carbohydrate, 5-32; glycogen, 15*24; 

 other polysaccharides, 1-78; together with some substances 

 of undetermined composition. Similar analyses have been 

 made by other authors. § It is to be remembered that all 



* Fosse : " Compt. rend.," 1912, 155, 851 ; 1913, 156, 567, 1938 ; 1914- 

 J58, 1374 ; I59» 253. Verschaffelt : " Pharmaceut. Weekblad," I9i4' 5l» 

 189. 



flvanoff: " Biochem. Zeit.," 1923, 135, i; 136, i, 9; «43, 62; 1925, 

 162, 425; 1926, 175, 181. 



X Kiesel : " Zeit. physiol. Chem.," 1925, I50» I49- 



§ See Lepeshkin : " Ber. deut. bot. Gesells.," 1923, 41, 179- Ivanow : 

 "Biochem. Zeit.," 1925, 162, 441. 



