228 MUSCULAR SYSTEM. 



the straight direction produces on the bones into which it 

 is inserted? 



.#. Take the direction of the muscle from its fixed to 

 its moveable point, then take the inverse of this course, 

 and you have the direction of the motion. 



Q. How do you estimate the action of a broad muscle, 

 which is united in a single tendon or point? 



./?. Take the middle line of direction of all its fibres. 



Q. And how, when the fibres attached at two points 

 form several fasciculi? 



>ft. You must estimate the line of the direction of each 

 fasciculus, and then you can decide on the action of the 

 muscle. 



Development of the Muscular System of Animal 



Life. 



Q. What is the colour of the muscles in the foetus? 



A. The tinge is that of venous blood. 



Q. What excites the action of the muscles so univer- 

 sally as they are seen to be at the moment of birth? 



Ji. The contact of air, which excites the brain to per- 

 ception of impressions new to it; then the diaphragm is 

 excited to motion, and respiration sends red blood to the 

 brain; this blood proving an additional stimulus to cere- 

 bral influence, the constant and active muscular motions 

 of infancy are produced. 



Q. What effect has disease on the colour of the mus- 

 cles? 



.#. Acute diseases have little effect; in chronic cases it 

 often becomes pale; in dropsy it is quite pale. 



