268 



The Structure of Protoplasm 



Fig. 1. This figure is by Dr. 

 H. Mark and illustrates Dr. 

 Kurt Meyer's concept of the 

 molecular and micellar struc- 

 ture of elastic organic sub- 

 stances. The chains are mole- 

 cules, the segments in which 

 represent glucose units, or 

 rather a block of glucose units, 

 say fifteen in each segment. 

 The micel, or-h, would contain 

 some 500 glucose units. Many 

 of the molecular chains ex- 

 tend through two or more mi- 

 cel. The loose ends of the 

 chains are "fringes," always 

 present, so Meyer and Mark 

 believe. A somewhat similar 

 scheme of micels with over- 

 lapping ends is given in Fig. 

 5, page 6. 



The conditions which estabUsh mole- 

 cular form became evident from a com- 

 parison of acetylcellulose and acetyl- 

 amylose which are distinguished only 

 by the configuration of the glucosidal 

 bond, [3 in cellulose and a in amylose. 

 Molecules of acetylcellulose when in 

 solution are stretched and oriented by 

 streaming, as R. Singer has found in as 

 yet unpublished experiments; whereas, 

 the molecules of acetylamylose are not. 

 From this it follows that the molecules 

 of acetylcellulose are fibrous, and those 

 of acetylamylose are spherical.'^ 



Far better known is the relationship 

 between chain structure and rubber- 

 like elasticity. According to the theory 

 which was developed by us"*, and at 

 about the same time by W. Busse*^ and 

 E. Karrer', the tendency of rubber-like 

 matter to take its original form after 

 deformation can be ascribed to the fact 

 that the chain molecules themselves are 

 capable of deformation, and that parts 

 of adjacent chains can slide one over 

 the other just as do molecules in a 

 viscous fluid. Stretching and orienta- 

 tion force molecules, which when re- 

 laxed may assume any possible shape, 

 to take on less possible forms and ar- 

 rangements. Due to kinetic energy, the 

 thermodynamic probability that the 

 molecules shall assume a disordered 

 state becomes greater as soon as the ex- 

 ternal force causing deformation disap- 

 pears. It follows from this that only 

 systems containing chain molecules, the 

 inner mobility of which is not prevented 

 by crystallization or micel formation, 

 can possess rubber-like elasticity. In 



