14(5 NATURAL HISTORY. 



stretching is, when the spirits are a little heavy by 

 any vapour, or the like. For then they strive, as it 

 were, to wring out and expel that which loadeth 

 them. So men drowsy, and desirous to sleep, or 

 before the fit of an ague, do use to yawn and stretch, 

 and do likewise yield a voice or sound, which is an 

 interjection of expulsion : so that if another be apt 

 and prepared to do the like, he followeth by the 

 sight of another. So the laughing of another maketh 

 to laugh. 



Experiment solitary touching infectious diseases. 



297. There be some known diseases that are 

 infectious ; and others that are not. Those that are 

 infectious are, first, such as are chiefly in the spirits, 

 and not so much in the humours, and therefore pass 

 easily from body to body ; such are pestilences, lip- 

 pitudes, and such like. Secondly, such as taint the 

 breath, which we see passeth manifestly from man 

 to man, and not invisibly, as the affects of the 

 spirits do ; such are consumptions of the lungs, &c. 

 Thirdly, such as come forth to the skin, and 

 therefore taint the air or the body adjacent, espe 

 cially if they consist in an unctuous substance not 

 apt to dissipate, such are scabs and leprosy. Fourthly, 

 such as are merely in the humours, and not in 

 the spirits, breath, or exhalations ; and therefore 

 they never infect but by touch only ; and such a 

 touch also as cometh within the &quot; epidermis ;&quot; as 

 the venom of the French pox, and the biting of a 

 mad dog. 



