Physiology of the Muscles. 497 



gen is conveyed to all parts of the system by the blood, especially by 

 the red corpuscles. And wherever it is, it must be in close contact 

 with the oxidizable tissues. But for some reason these two elements, 

 viz. , the oxygen of the blood and the carbon of the tissues, appear to 

 be unable to unite, hungry as they may be supposed to be for each 

 other. But this union can take place only on conditions. Carbon, in 

 some forms, is very slow to unite with oxygen. As charcoal, it may be 

 exposed to oxygen a long time without change. Oxygen itself, as we 

 have seen, may be met with in very different conditions. As ozone, its 

 intensity and force are very greatly increased, and in that state it is 

 competent to form unions which it cannot form in its ordinary state. 

 But an electric current, even a feeble one, is competent to rearrange the 

 molecules of oxygen into molecules of ozone. According to Draper, 

 that is what takes place. Wherever the nervous current is sent, the 

 oxygen in the blood in reach of such current becomes ozone, and then, 

 by virtue of its more intense combining power, it at once combines with 

 some of the constituents of muscle, developing heat and electricity. It 

 can scarcely be doubted that the muscle contraction which follows is 

 due chiefly, if not entirely, to the sudden magnetization of the muscle 

 by the electricity thus generated. No doubt the sudden abstraction of 

 the many molecules of the muscle tissue which then takes place, con- 

 tributes to the facility and extent of the contraction by enlarging the 

 molecular spaces in the muscle ; but the efficient cause of the contrac- 

 tion is the energy of the contractile electric or magnetic tensions estab- 

 lished in the muscle. These tensions are exhausted and abolished each 

 time the muscle contracts, and renewed each time a pulsation or wave 

 of the current is shot down the nerve from the brain or spinal cord. 



Physiologists are not agreed as to the detail of the causes of muscle 

 contraction, or of the production of ozone in the blood. Antozone as 

 well as ozone is produced, and it certainly cuts an important figure ia 

 the chemical reactions which take place. ( Landois. ) All the reactions 

 produce heat and electricity, even when the body is at rest. The move- 

 ment of the blood even in sleep does this. And it is not improbable 

 that there is a partial storage of electricity in the muscle fibres accumu- 

 lating during the process of repair which goes on during periods of rest- 

 ing. This happens in the case of the electric fishes, ,and the liberation 

 of this stored energy is made, in their case, by the voluntary discharges 

 down the motor nerves from the brain. If there is such a storage in 

 the case of the voluntary muscles, it is obvious that the current from 

 the brain down the nerves operates in some analogous way to discharge 

 the tensions, and permit their conversion into muscle contraction. 



The nerve tension is generated in precisely the same way in which the 

 muscle tension is generated ; but its tension may become exhausted in 



