THE OXIDIZING SUBSTANCE AND MYOSINOGEN. 'J.'J") 



be a strong one if the full meaning of the following sentence 

 from Foster's "Physiology" (sixth edition) is gathered: "We 

 might compare a living muscle to a number of fine, trans- 

 parent, membranous tubes containing blood-plasma." If we 

 also recall the fact that capillaries do not possess contractile 

 fibers and that arterioles represent the ultimate subdivision 

 to which vasomotor nerves are distributed, it becomes clear 

 that we have all the mechanical elements necessary to account 

 for some unexplained phenomena that attend muscular con- 

 traction. An impulse capable of causing a change of caliber of 

 a peripheral arteriole would thus suddenly admit more arterial 

 blood i.e., more oxygen-laden plasma into the "fine, trans- 

 parent, membranous tubes," and contraction, an inherent 

 property of muscular tissue, would follow. 



The prevailing views as to the nature of the process 

 through which the mechanical energy utilized during muscular 

 activity cause contraction or retraction may be illustrated by 

 selections from Professor Foster's text. Referring to the 

 chemical analogy between the axis-cylinder and muscle-tissue, 

 he says: "We have no satisfactory evidence that in a nerve 

 even repeated nervous impulses can give rise to an acid re- 

 action" . . . "nor have we satisfactory evidence that the 

 progress of a nervous impulse is accompanied by any setting 

 free of energy in the form of heat." In the summary, referring 

 to the terminal phenomena, he remarks: "This muscle-impulse, 

 of which we know hardly more than that it is marked by a 

 current of action, travels from each end-plate in both direc- 

 tions to the end of the fiber, where it appears to be lost; at 

 all events, we do not know what becomes of it. As this im- 

 pulse-wave, whose development takes place entirely within the 

 latent period, leaves the end-plate, it is followed by an explosive 

 decomposition of material, leading to a discharge of carbonic 

 acid, to the appearance of some substance or substances with 

 an acid reaction, and probably of other unknown things, with a 

 considerable development of heat. This explosive decomposi- 

 tion gives rise to the visible contraction-wave, which travels 

 behind the invisible muscle-impulse at about the same rate, 

 but with a vastly increased wave-length. The fiber, as the wave 

 passes over it, swells and shortens, and thus brings its two 



