CIRCULATION. 141 



sage through that pipe, is inferior in impetus and velocity to the 

 blood gushing through the whale's heart." 



But if we are astonished in reflecting what must take place in 

 the aorta of the whale, our admiration will be not less excited on 

 examining the circulation even in the web of a frog's foot. When 

 this is brought under a moderately powerful microscope, we can 

 perceive with ease through the transparent coats of the tiny vessels, 

 the red globules of the blood in some singly, with long intervals 

 between in others, two abreast and, in others still, numbers 

 crowded together pursuing their beautiful course, like the trains 

 of spectral figures that pass before us in our dreams now moving 

 onwards with the most steady regularity, and again hurried forward 

 by the struggles of the little animal. This sight, an excellent 

 writer well observes, " is one which no man who has once seen can 

 ever forget ; and he who has not seen it, has not seen one of the 

 most curious, and wonderful, and beautiful objects which animated 

 nature presents." 



Like most of the organs of organic life, the heart, in its usual 

 state, gives us but slight indications of sensibility. Harvey met 

 with an extraordinary opportunity of showing this. A young 

 nobleman, from disease, had the heart exposed, so that it could 

 even be handled while beating ; and Harvey, to his astonishment, 

 found that, unless his fingers came in contact with the outer 

 skin, the young man was altogether unconscious of the heart being 

 touched. Though nearly destitute of the sensations of touch, 

 however, the heart is instantly affected by every powerful bodily 

 excitement, or strong mental emotion. Upon the first of these de- 

 pends the use physicians make of the pulse (which is just the 

 heart's beat transmitted through the arteries) in judging of the dif- 

 ferent bodily ailments ; while the power of emotions over the heart 

 has furnished the poetry of all languages with some of its strongest 

 images. The capillaries also share in the influence of emotions, 

 of which we have a familiar example in blushing. 



The greater or less vigor with which the blood is circulated 

 through the system, gives rise to important effects. We see this 

 particularly in two forms of constitution. In the one, the circula- 

 tion is very vigorous ; all the functions are performed with energy ; 

 and the diseases in general are of an acute character. When the 

 complexion is fair, this constitutes what has been called the sanguine 

 temperament when dark, the choleric. In the other variety, the 

 circulation, and all the functions connected with it, are languidly 



