CONVERSION 119 



of which is the abandonment of the form proteid in favor of protein, a 

 usage which will no doubt soon come to prevail. 



LITERATURE or PROTEID SYNTHESIS. The subject of proteid syn- 

 thesis is summarized in the works of PFEFFER and of JOST. There is 

 also matter of importance in LOEB'S "Dynamics of Living Matter" 

 (New York, Columbia University Press, 1906), and incidentally some 

 notes of interest in BARNES' address, mentioned later under Respira- 

 tion. Upon nitrification of soils there is an admirable address by 

 WARD in Nature, 56, 1897, 455 (and earlier in Science Progress, 3, 

 1895, 251), and there is an excellent discussion in Chapters X and XI 

 of FISCHER'S "Structure and Functions of Bacteria" (translated by 

 JONES, Oxford, Clarendon Press, 1900). Upon water-culture, in 

 addition to the works cited, the latest important paper is by SCHIMPER 

 in Flora, 73, 1890, 207. 



4. CONVERSION. 

 (ASSIMILATION PROPER, INCLUDING DIGESTION.) 



Having traced the synthesis of the basal carbohydrate and 

 (so far as known) of the basal proteid, it is next essential to 

 trace their conversion into the great variety of organic substances 

 of diverse special functions and meanings which they form, 

 a transformation effected as a rule with slight or no changes of 

 energy relations. The study is largely one of organic chemistry, 

 involving, in its advanced and quantitative phases, special man- 

 ipulation of great difficulty, but in its simpler and qualitative 

 phases, practical manipulation which is time-consuming rather 

 than difficult. It will be a great aid to the student, giving the 

 subject a far clearer and more nearly objective meaning, if he 

 can come into personal contact with it through some of the 

 latter type of experiment, which he can do by aid of the following: 



SUGGESTED EXPERIMENTS. Prepare, examine macroscopically and 

 microscopically, apply the more prominent tests to, and observe the more 

 prominent reactions of the common and important carbohydrates and pro- 

 teids of the plant, following as a guide the excellent directions in DETMER, 

 258, 293, or of DARWIN and ACTON, 249. There are also good directions 

 in SNYDER'S "Chemistry of Plant and Animal Life" (New York, Macmillan, 

 1903). There should also be included a polariscopic study of starch and 

 other bodies of definite structure; a polarizer and analyzer arranged for 

 the microscope are obtainable from ZEISS at a cost of about 40 marks. 



