USEFULNESS OF PHYSIOLOGICAL KNOWLEDGE. 21 



lungs are called into play as powerfully as in running 

 or any other species of severe muscular exercise. 

 From net adverting to this fact, a strongly consti- 

 tuted individual, who brought on spitting of blood 

 by bodily labour to which ho had not been accus- 

 tomed, conceived himself perfectly safe, and even 

 cautious, when he gave up the spade, and confined 

 himself to talking a great deal, which he did daily 

 to numerous visiters in explanation of favourite 

 views then occupying all his thoughts. The con- 

 sequence was, that the medical treatment resorted 

 to was without effect, and a fatal illness was brought 

 on. When the action of the lungs was subsequently 

 explained to this individual, he saw at once the 

 error into which he had fallen, and lamented the 

 ignorance which had led to it, but too late to derive 

 any advantage from his knowledge. 



We are constantly meeting with anomalies in 

 practical life, in the case of individuals little accus- 

 tomed, when in health, to observe or reflect on the 

 influence of external circumstances and modes of 

 life in disturbing the action of the various animal 

 functions, but at the same time easily and deeply 

 impressed by all extraordinary occurrences affecting 

 them. Thus, when any one is taken ill, his relatives 

 or friends become extremely anxious to have his 

 room properly ventilated ; his body-clothes fre- 

 quently changed and carefully aired ; his food prop- 

 erly regulated in quantity and quality ; his skin 

 cleaned and refreshed ; his mind amused and tran- 

 quillized ; his sleep sound and undisturbed ; and his 

 body duly exercised ; and they state as the reason 

 for all this care, and most justly, that pure air, clean- 

 liness, attention to diet, cheerfulness, regular ex- 

 ercise, and sound sleep are all highly conducive to 

 health And yet such is the inconsistency attendant 

 on ignorance, that the patient is no sooner restored, 

 than both he and his guardians are often found to 

 become as careless and indifferent in regard to all 



