THE MANIFESTATIONS OF LIFE 91 



seen in the most simple forms of life i.e., the cells and 

 consist of cell-division. This is a manifestation the 

 cause of which has long been sought by biologists with 

 little success. It was at one time supposed to depend 

 upon some simple physical condition and even attributed 

 to disproportions between the absorbing surface through 

 which the cell was nourished and the amount of cell 

 contents to be nourished. 



Thus, as a cell grows the contents increase in three 

 dimensions while the surface increases in but two. It 

 was supposed that when a certain cubical content was 

 reached, the cell became embarrassed by its inability to 

 secure nourishment and so. was compelled to undergo 

 some compensatory change, the most frequent being 

 division. This explanation is, however, inadequate, for 

 among cells whose nourishment is effected through the 

 intracellular digestion of ingested food particles it could 

 not apply. 



It would seem, therefore, to be a hereditary peculiarity 

 of the cell and to be determined by chemical conditions 

 intrinsic in the cell itself. 



This inability to fully comprehend the conditions 

 leading to multiplication or reproduction forbids an 

 intelligent understanding of the process and limits us 

 to the description of what is to be seen without enabling 

 us to explain it. 



REFERENCES. 



O. HERTWIG: "Die Zelle und die Gewebe," Jena, 1892, 1905 

 MAX VERWORN: "Allgemeine Physiologic," Jena, 1909. 

 H. S. JENNINGS: " Behavior of the Lower Organisms," N. Y., 1906. 

 JACQUES LOEB: "The Dynamics of Living Matter," N. Y., 1906. 

 E. STRASBURGER, H. SCHENCK, F. NOLL, AND G. KARSTEN. "A 



Text-book of Botany," Third English Edition by W. H. 



Lang, N. Y. and London, 1908. 



