myosin contains three meromyosins, while if Weber's value is 

 correct, it contains six. Assuming the smaller value to be correct, 

 the myosin molecule would look something like Fig. 1 . Of the two 

 kinds of meromyosins one is somewhat plumper and sediments 

 faster and has been called H-meromyosin, the H standing for 

 "heavy." In Fig. 1, arbitrarily, it is placed into the middle. The 



«• 



s 



i 



s 

 < 



•m 

 •m 





Fig 1 



a b 



Fig 2 



Fig. 1. Schematic representation of a myosin molecule, consisting of 

 one H and two L meromyosins. Sequence of meromyosins arbitrary. 



Fig. 2. a: Schematic representation of the myosin molecule of Fig. 1, 

 as consisting of protomyosins. b: Possible rearrangement of protomyosins 

 in contraction. 



Other two are more slender and have been called L-meromyosins, 

 L standing for "light," these having a lower sedimentation con- 

 stant. There are two L's for every H. 



What makes it difficult to bring this discovery into agreement 

 with earlier concepts is that only the H interacts with ATP, re- 

 leasing the energy of its '^P's, while there is every reason to be- 

 lieve that the L's are involved in contraction, do the work, and use 

 the energy. The energy would have to get, somehow, from the 

 H's to the L's and it is difficult to see how a bond energy could 



