n8 



Scientific Proceedings (92). 



process-chain of reactions reaches a stage wherein are found, in 

 place of one cell, two cells, which if the division be equational are 

 exact duplicates of the one parent cell at the same stage. If, 

 however, the mitosis be ontogenetic the daughter cells will exactly 

 resemble the parent cell at the latter 's comparable stage in chro- 

 matin content only; their cytoplasmic form and functions may 

 vary greatly. 



The structural stages and ends of the mitotic process have been 

 analyzed much more thoroughly than have the dynamical. The 

 analysis of the latter seeks not to find form but to explain what is 

 happening in terms of interplay of forces. It should yield even 

 greaterreturns in understanding vital and evolutionary phenomena. 

 In attempting such an analysis it is necessary first to learn how to 

 measure 1 a characteristic of mitotic activity, such as its velocity in 

 passing through successive stages. The actively dividing cell 

 must then be subjected to definite measures and quality of light, 

 heat, gravity, pressure, electricity, or chemical influence, and 

 next the behavior of the dividing cell as modified by the definite 

 quantitative and qualitative influences must be measured. We 

 may then examine the behavior of such elementary processes as 

 have been measured while reacting to these definite influences. It 

 is finally in order to seek for similarity of behavior which, when 

 found, suggests very strongly similarity of organization and forces. 

 The completeness and accuracy of such an analysis depends, of 

 course, upon the degree of refinement in the isolation and measure- 

 ment of factors and the exactness of the parallel to known processes. 



This takes us immediately into the realm of physical chemistry. 

 The present paper will discuss a definite problem in this study, 

 namely, the influence of temperature upon the dividing root-tip 

 cells of the onion, and will then seek a preliminary or working 

 analysis by comparing the reaction thus found with similar reactions 

 which physical chemists have found in other and simpler complexes. 

 The following table shows the effect of temperature upon the 

 velocity of the several mitotic stages calculated in the usual Q i0 

 form of the chemist. 



1 Laughlin, H. H., "The Duration of Mitotic Stages in the Root-tip Cells of the 

 onion," Carnegie Inst, of Wash. Pub., No. 267. 



