( 



GENERAL PHENOMENA OF LIFE 29 



during the division of the cell by the process of karyokinesis as well 

 as from its pecuUar staining reactions. Thus, we find that the growth 

 and activity of the cell is accompanied by definite variations in the 

 size and appearance of the chromatin elements. In the egg of the 

 shark they are small at first and stain deeply, while later on they 

 lose their staining qualities and increase in mass. At maturity, the 

 chromosomes again become smaller and finally break up into fine 

 granular bodies possessing an intense affinity for nuclear dyes. Re- 

 garding the chemical differences between the nucleus and the cytoplasm, 

 little is known. The proteins of living substance are conjugated in 

 their nature, because the simple proteins are here combined with 

 other complex bodies. They present, however, certain distinct 

 differences in that those of the nucleus form the class of the nucleo- 

 proteids, while those of the cytoplasm are largely compounds of protein 

 and lecithin. The former are characterized by their content in 

 phosphorus and by their decomposition products of nuclein and pro- 

 tein. Nuclein which seems to be the chief constituent of the nuclei 

 of cells, may be broken down into nucleic acid and protamine, the latter 

 presenting the characteristics of a protein substance. 



CHAPTER II 

 GENERAL PHENOMENA OF LIFE 



Growth and Metabolism. — ^Life may be investigated in different 

 ways. To begin with, the inquiry may be directed along chemical 

 lines, to discover not only the material entering into the composition 

 of Hving matter, but also the changes which this material undergoes 

 in the course of the vital processes. Special emphasis should in this 

 case be placed upon its metabolism, i.e., upon the changes presented 

 by it during its periods of assimilation and dissimilation. In the 

 second place, life may be investigated by physical means, at which 

 time the question regarding the energetics of protoplasm must be 

 most carefully considered. Living matter has been found to produce 

 energy in the form of mechanical energy, heat, light and electricity. 

 In the third place, it is possible to study either its gross or minute 

 structure, i.e., to pay special attention to the form in which it exists, 

 but naturally, life does not present itself exclusively in any one of these 

 ways, but as a homogeneous whole. These methods, therefore, are 

 Employed merely for the purpose of analyzing this process from differ- 

 ent standpoints. One amplifies the other. 



Living substance is always in activity. It grows; it secretes; it 

 moves from place to place and naturally, all these processes require work 

 and the production of energy which is derived from the union of its dif- 



