346 PHYSIOLOGY AND HEALTH. 



insensibility, may follow. It needs and receives more blood 

 during its action and excitement, and less in its quiescence 

 and calmness. The heart must therefore be in good health, 

 and able to supply the greater want of the active and excited 

 brain. But, when the heart is diseased, it cannot send this 

 increase of blood ; and, if it attempts it, it struggles in vain, 

 and great distress, and even death, may follow. Persons who 

 suffer from disease of the heart, cannot safely bear any 

 mental excitement. For this reason, a celebrated surgeon, 

 who had this disease, continually guarded himself against 

 any irritation of temper or agitation of mind, yet was sud- 

 denly excited on an occasion, arid immediately died. 



795. The connection of the brain with the lungs is not 

 less apparent than witli the heart. The brain needs not 

 merely a large quantity of blood, but that of the purest and 

 the best quality. Whenever the blood is imperfectly purified 

 of its carbon, either from defect of the respiratory appara- 

 tus or from want of pure air, the brain feels it immediately. 

 If the waste and dead particles are not carried off from the 

 blood in the lungs, the impure blood is sent again through 

 the heart and arteries to supply the body ; the brain surfers 

 more than the other organs, and becomes inactive, and often 

 painful, and the mind dull. The audience of a close and 

 crowded lecture-room, and children in an unventilated 

 school-room, lose their mental energy and their power of 

 application. ( 383, 384, p. 165.) 



796. The sympathies between the brain and stomach are 

 familiar to us. Most men have been compelled to know 

 how these two organs suffer together in sick headache. The 

 frequent pains in the head are generally to be referred to the 

 derangement of the stomach, and, when this organ is relieved, 

 the brain is usually well. Dyspeptics complain of much 

 headache, and, on the contrary, those who suffer from disease 

 of the brain are often troubled with digestive disturbance. A 

 blow on the head will often occasion vomiting, and excess 

 of action of the brain will sometimes suspend the action of 

 the organs of digestion. 



