THE STRUCTURE OF PROTOPLASM 



253 



shows how well tensile-strength values agree with X ray analyses 

 of symmetry: 



Mark adds another possibility, viz., that of pronounced over- 

 lapping of the molecules of one bundle with those of another 

 (Fig. 134A), a very likely condition in that the molecular chains 

 of a cellulose micelle are of different lengths. Such an arrange- 

 ment would provide maximum strength in the direction of the 



Fig. 134. — A, orientation of molecular chains in cellulose, orderly and parallel 

 to the fiber axis, but terminal boundaries irregular; B, random arrangement of 

 molecular aggregates. {After Carothers.) 



fiber axis, because the mutual cohesive force of the long chains 

 would be fully utilized. In regeneration cellulose (cellophane), 

 says Carothers, there is random orientation (Fig. 134B). The 

 molecules are brought into an ordered arrangement by mechan- 

 ical stress. The strength of a sheet of cellophane which is 

 initially the same in all directions can be so changed by stretching 

 that its strength along the axis of stretch is increased several 

 times. 



If we turn for a moment to other substances of an organic 

 nature which have been subjected to X ray study and found 

 to be crystalline in nature, with linear units in often orderly 



