70 INTRODUCTION TO CYTOLOGY 



A number of biologists (Gruber 1886, Hertwig 1898, Heidenhain 1894, 

 Henneguy 1896, Conklin 1902) concluded that in general the chromo- 

 somes (basichromatin) are concerned chiefly with differentiation and 

 regulation, while the achromatin (oxychromatin) has to do with metabo- 

 lism (Conklin 1917). Metabolism is in reality a great complex of 

 reactions: the reactions are not independent of one another but are closely 

 correlated, and thus constitute an intricately adjusted reaction system. 

 Among these many reactions, according to modern physiology, the most 

 important is oxidation, for the energy utilized by the organism is derived 

 immediately from the union of protoplasm or of its constituent elements 

 with oxygen. Oxidation has been called the "independent variable" 

 (Loeb and Wasteneys 1911) upon which the other reactions largely 

 depend: oxidation is the dominant factor in cell activity, and it is there- 

 fore of the greatest importance to understand as well as possible the rela- 

 tion of the parts of the cell to this process. 



Following the experiments of Spitzer (1897), who observed thatnucleo- 

 proteins extracted from certain animal tissues have the same oxidizing 

 power as the tissues themselves, it was advocated by Loeb (1899) that the 

 nucleus is the center of oxidation in the cell. Loeb pointed out that this 

 would explain the inability of enucleated cell-fragments to undergo 

 regeneration. This conclusion was supported by R. S. Lillie (1903), who 

 later (1913) showed that rapid oxidation occurs both at the surface of the 

 cell and at the surface of the nucleus, and also by Mathews (1915). Other 

 workers (Wherry 1913, Schultze 1913, Reed -1915) however, have failed 

 to agree. Osterhout (1917), who briefly summarizes the subject, found 

 that "injury produces in the leaf-cells of the Indian Pipe (Monotropa 

 uni flora) a darkening which is due to oxidation. The oxidation is much 

 more rapid in the nucleus than in the cytoplasm and the facts indicate 

 that this is also the case with the oxidation of the uninjured cell." 



The role of the nucleus in development and inheritance, which has 

 been a subject of so much discussion in recent years, will be dealt with 

 in later special chapters (XIV-XVIII), after the behavior of the nucleus 

 in somatic cell-division, maturation, and fertilization has been described. 



Bibliography 4 



Nucleus 

 BAILEY, I. W. 1920a. The cambium and its derivative tissues. II. Size variations 



of cambial initials in gymnosperms and angiosperms. Am. Jour. Bot. 7: 355- 



367. figs. 3. 

 19206. The cambium and its derivative tissues. III. A reconnaissance of cytolog- 



ical phenomena in the cambium. Ibid. 7: 417-434. pis. 26-29. 

 BALBIANI, E. G. 1881. Sur la structure du noyau des cellules saliyaire chez les 



larves de Chironomus. Zool. Anz. 4: 637-641. figs. 7. 

 BKRGHS, J. 1909. Les cineses somatiques dans le Mnrsilia. La Cellule 25: 73-84. 



Ipl. 



