The Dynamics of Cell-Division. 



121 



Of the processes here listed 1 8 were secured from Kanitz's com- 

 pilation, 2 8 from Snyder's, 3 one — that of Qio values of the several 

 mitotic stages — was supplied by the experiments of the writer, 4 

 and the remainder were found either in isolated cases in the litera- 

 ture of related subjects, or one current in text-books. 



These are the materials at present available for beginning the 

 analysis of the dynamics of mitosis by means of differential tem- 

 perature-reactions. The question is, which, if any, of the more 

 elementary of these forces, and what other forces, in what com- 

 bination and to what degree, are active in each stage of mitosis? 

 Certainly for the most part the several mitotic stages are mani- 

 festations of chemical and physico-chemical forces showing a 

 positive index. 



Stages Nos. i and 6 deserve special attention. Stage No. I 

 is the earliest prophase; Stage No. 6 is that in which the chromo- 

 somes have left the equator but have not yet reached the poles. 

 Both of these stages manifest a negative coefficient from io° C. 

 to 20° C. The activities of these stages within such temperatures 

 must, therefore, as shown by the behavior of their resultants of 

 forces, be composed of those processes most of which, or at least 

 the most effective of which, react negatively to temperature 

 increments. This fact alone halves the complexity of the puzzle 

 for these particular mitotic stages, and sets them apart as being 

 characterized by distinctive sets of forces. 



Another general observation is worthy of note, physiologists, 5 

 point out that in simple chemical processes Q i0 values are greater 

 in the upper ranges of temperature than in the lower, while in 

 vital processes generally the reverse is true. In mitosis the com- 

 plex of forces is such that in most stages a given increment of tem- 

 perature will cause a greater velocity-response in the particular 



1 The references to each of the experiments providing the listed data on Qw values 

 will be given in the completer paper now being prepared by the writer. 



2 Kanitz, A., "Temperatur und Lebensvorgange." Berlin, 1915. 



3 Snyder, Charles D., "A Comparative Study of Temperature coefficients of 

 the Velocities of Various Physiological Actions," Ant. Jr. Physiol., Vol. XXII, Aug., 

 1908. 



4 Loc. cit. 



5 Harvey, E. Newton, "Effect of Different Temperatures on the Medusa cas- 

 siopea. With Special Reference to the Rate of Conduction of the Nerve Impulse." 

 Carnegie Inst, of Wash. Pub. 132. 1910. 



