34 



Physiology. 



low tube has greater strength than the same amount of 

 material in the form of a solid cylinder. The long bones 

 of the limbs are hollow, and near their ends, where we 

 have found that they need to be enlarged, we find a 

 spongy structure, where lightness and strength are secured, 

 by the interlacing fibers and plates of bony material. 



Muscles always Stretched. The muscles are always 

 slightly stretched, as shown by the fact that when a cut 



,, is made into a muscle the 



wound gapes open ; the ten- 

 sion of the muscle is further 

 shown by the fact that when 

 a bone is broken, as in the 

 upper arm or thigh, the ends 

 of the bones slip by each 

 other, and the limb has to be 

 strongly stretched to bring the 

 ends back together. Muscles 

 act better when slightly 

 stretched, and probably need a 

 slight resistant action of the 

 opposing muscle. 



Fig. 22. Fracture of the Humerus. 



Effect of Alcohol on the Mus- 

 cles. "A paralytic symptom, 

 which is erroneously regarded as one of stimulation, is also 

 found in the deadening of the sense of fatigue. There is 

 a strong belief that alcohol gives new strength and energy 

 after fatigue has set in. The sensation of fatigue is one 

 of the safety valves of our machine. To stifle the feeling 

 of fatigue in order to be able to work on, is like forcibly 

 closing the safety valve so that the boiler may be over- 

 heated. 



