Animal Morphology. 121 



Encase as was once done by an artist, in taking a cast 

 of the chest of a pugilist the entire thorax in a wall of 

 plaster of Paris, and in much less time than an hour the 

 sufferer would be dead from asphyxia. 



For why ? Because the expansion and contraction in 

 the air cells of the lungs is the minimum of respiratory 

 action, carried on by inflating and compressing the lungs, 

 through the medium of unstriped muscle ; for the inter- 

 costal and abdominal muscles, with the diaphragm, have by 

 far the most to do with the respiratory function ; and in 

 the spinal cord the respiratory tract of Sir C. Bell is the 

 chief ministrator of nerve tissue to these parts, but by no 

 means the only one. 



These muscles never cease, save by an effort of the will, 

 to act day and night from year's end to year's end quite as 

 much as the heart. Life hangs on the balance of this 

 continuous action, and, so to speak, the major action is as 

 involuntary as is the peristaltic action of the bowels. 



Hence striped muscle is, under certain conditions, as uni- 

 form in its action, and as constant, as the beaded muscles of 

 the vegetative organs ; whilst those striped muscles be- 

 longing to the limbs, etc., take rest as much as the senses 

 do during sleep. Of course, in muscular structure, in 

 health there is, whether contracting or not, a certain 

 amount of tenacity or vitality, which appears to always 

 hold them in readiness for action ; but, so far as direct con- 

 traction and relaxation are concerned, they are in sleep, and 

 at many other times, motionless. 



It is evident that the functions of locomotion and rest 

 are so blended in these two senses, force and touch, the 

 latter being the sense that most incites to rest smoothness, 

 calmness, and softness or repose that the continuous 

 action of one is adverse to the other, and co-ordination 

 of functions, in relation to the securing an end, is essential. 



