CHAPTER XII 



CELL MECHANICS 



Postulates — Unity of Mitosis and Meiosis — Internal Mechanics — The 

 Spiralisation Cycle — The Molecular Spiral — External Mechanics — Specific 

 Attractions — Gene Reproduction — Repulsions — Terminalisation — Centromere 

 and Centrosomes — The Spindle — Congression and Orientation — Cell-Wall 

 Formation — The Balance Theory of Mitosis — Ultra-Mechanics — Crossing-Over 

 and Structural Change^Molecular Foundations. 



Utinam caetera naturae phenomena ex principiis mechanicis eodem argu- 

 mentandi genere derivare liceret. Nam multa me movent, ut nonnihil 

 suspicer ea omnia ex viribus quibusdam pendere posse, quibus corporum 

 particulae per causas nondum cognitas vel in se mutuo impelluntur et secundum 

 figuras regulares cohaerent, vel ab invicem fugantur et recedunt.* 



Newton, Principia Alathematica, Pref. ist Ed., 1686. 



I. INTRODUCING AN AXIOMATIC 



In studying movements in the cell, our object must be to 

 find out how far they are consistent and hence to infer the principles 

 governing their occurrence. Such mechanical principles must be 

 related if possible to those inferred in other systems, especially 

 non-living systems both of a molecular and of a macroscopic order 

 of size and integregation. The most promising method at first 

 sight would seem to be the method of externally controlled experi- 

 ment which has proved most useful in the analysis of other physio- 

 logical processes. This method has in fact yielded important, if 

 somewhat isolated, results. But they have been limited in scope 

 by difficulties of a similar kind to those that have limited the studies 

 of electrons. It is difficult to observe the living chromosomes 

 without altering them. It is usually impossible to alter them in 

 one respect without altering them in several others and by means 

 which cannot be exactly defined. 



* I wish we might derive the rest of the phenomena of nature by the same 

 kind of reasoning from mechanical principles, for I am led by many reasons 

 to suspect that they may all depend upon certain forces by which in an 

 unknown way the particles of bodies are either mutually attracted towards 

 one another and cohere in regular figures, or are repelled and recede from one 

 another. 



479 



