62 HUMAN PHYSIOLOGY 



2. If the processes of combustion, upon which the contraction 

 and work of muscles depend, took place in the capillary blood of 

 the muscle, the muscle fibre would be forced to do its work by 

 transforming the heat, supplied to it from the blood, into- 

 mechanical work. By heating the muscle fibre, however, we are 

 not able to obtain as powerful contractions as by physiological 

 stimulation, if we do not use temperatures which destroy the life 

 of the muscle (see heat-rigor, Chapter XIV). Besides this, 

 muscles from which the blood has been removed by injecting, 

 physiological salt solutions, and even isolated muscles, can, by 

 stimulation, be made to contract. 



