From the Havemeyer Chemical Laboratory, New York University, New York 



A NEW EXPLANATION OF THE MECHANICS OF 



MITOSIS 



BY 



ARTHUR B. LAMB 



With Two Figures 



The almost universal recurrence of essentially the same regular 

 arrangement of the chromatin substance in dividing cells indicates 

 emphatically that the same very definitely acting force or complex 

 of forces is operative in them all. Numerous suggestions have 

 been made as to what this omnipresent force may be, but none of 

 them have been able to meet the many requirements of the prob- 

 lem. Moreover, our real knowledge of the whole matter is so 

 scanty that any explanation seems at present a little premature. 

 I am, nevertheless, going to offer still another explanation of this 

 phenomenon; first, because it may prove suggestive to others and 

 may prompt fresh observation, and second, because it calls attention 

 to a phenomenon which deserves the consideration of cytologists, 

 whether it has any application to the present case or not. 



The marked polarity which mitotic figures exhibit, best de- 

 scribed by saying that they resemble the configuration assumed by 

 iron filings between unlike magnetic poles, together with the move- 

 ments which the chromatin substances execute about one another 

 oblige us to believe that this unknown force is of a polar nature, 

 that is, acts outward from a center and exerts its influence at a 

 distance. The only objection to this conclusion is that a crossing 

 of astral rays has been observed. The lines of force in the field 

 of any polar force cannot, however, cross, and consequently the 

 astral rays which would be assumed to follow these lines of force 

 also cannot, or should not, cross. This crossing, though certainly 

 real, is not, apparently, the prevailing condition, and it can be 



The Journal of Experimental Zoology, vol. v, no. i. 



