132 WILLIAM HARVEY 



Further, a certain impulse or force, as well as an im- 

 peller or forcer, such as the heart, was required to effect 

 this distribution and motion of the blood; both because 

 the blood is disposed from slight causes, such as cold, 

 alarm, horror, and the like, to collect in its source, to 

 concentrate like parts to a whole, or the drops of water 

 spilt upon a table to the mass of liquid; and because 

 it is forced from the capillary veins into the smaller rami- 

 fications, and from these into the larger trunks by the 

 motion of the extremities and the compression of the mus- 

 cles generally. The blood is thus more disposed to move 

 from the circumference to the centre than in the opposite 

 direction, even were there no valves to oppose its motion; 

 wherefore, that it may leave its source and enter more 

 confined and colder channels, and flow against the direc- 

 tion to which it spontaneously inclines, the blood requires 

 both force and impelling power. Now such is the heart 

 and the heart alone, and that in the way and manner 

 already explained. 



CHAPTER XVI 



THE CIRCULATION OF THE BLOOD is FURTHER PROVED FROM 

 CERTAIN CONSEQUENCES 



THERE are still certain problems, which, taken as con- 

 sequences of this truth assumed as proven, are not with- 

 out their use in exciting belief, as it were, a posteriore; 

 and which, although they may seem to be involved in 

 much doubt and obscurity, nevertheless readily admit of 

 having reasons and causes assigned for them. Of such 

 a nature are those that present themselves in connexion 

 with contagions, poisoned wounds, the bites of serpents and 

 rabid animals, lues venerea and the like. We sometimes 

 see the whole system contaminated, though the part first 

 infected remains sound; the lues venerea has occasionally 

 made its attack with pains in the shoulders and head, and 

 other symptoms, the genital organs being all the while un- 

 affected; and then we know that the wound made by a 

 rabid dog having healed, fever and a train of disastrous 

 symptoms may nevertheless supervene. Whence it ap- 





