182 DISEASES CLASS II. 1. 3. 



by certain animal motions of the terminations of the vessels. 

 Hence a new kind of gland is formed at the terminations of the 

 vessels in the eruptions of the small pox; the animal motions of 

 which produce from the blood variolous matter; as other glands 

 produce bile or saliva. Now if some of this matter is introduced 

 beneath the cuticle of a healthy person, or enters the circulation, 

 and excites the extremities of the blood-vessels into those kinds 

 of diseased motions, by which it was itself produced, either by 

 irritation or association, these diseased motions of the extremities 

 of the vessels will produce other similar contagious matter. See 

 Sect, XXXIII. .2. 5. and 9. Hence contagion seems to be pro- 

 pagated two ways; one, by the stimulus of contagious matter ap- 

 plied to the part, which by an unknown law of nature excites 

 the stimulated vessels to produce a similar matter; as in vene- 

 real ulcers, which thus continue to spread; or as when variolous 

 matter is inserted beneath the cuticle; or when it is supposed to 

 be absorbed, and diffused over the body mixed with the blood, 

 and applied in that manner to the cutaneous glands. The other 

 way, by which contagion seems to be diffused, is by some dis- 

 tant parts sympathizing or imitating the motions of the part first 

 affected; as the stomach and skin in the eruptions of the inocu- 

 lated small-pox, or in the bite of a mad dog; as treated of in 

 Sect. XXII. 3. 3. 



In some of the diseases of this genus, the pulse is strong, full, 

 and hard, constituting the sensitive irritated fever, as described 

 in the preceding genus; as in one kind of erysipelas, which re- 

 quires repeated venesection. In others the arterial action is 

 sometimes moderate, so as to constitute the sensitive fever, as in 

 the inoculated small-pox; where the action of the arteries is 

 neither increased by the sensorial power of irritation, as in the 

 sensitive irritated fever; nor decreased by the defect of that power, 

 as in the sensitive iriirritated fever. But in the greatest number 

 of the diseases of this genus the arterial action is greatly diminish- 

 ed in respect to strength, and consequently the frequency of pul- 

 sation is proportionally increased, as explained in Sect. XXXII. 

 2. 1. Which is owing to the deficiency of the sensorial power 

 of irritation joined with the increase of that of sensation, and thus 

 constitutes the sensitive inirritated fever; as in scarlatina with 

 gangrenous tonsils. 



From this great debility of the action of the arteries, there 

 appears to be less of the coagulable lymph or mucus secreted on 

 their internal surfaces; whence there is not only a defect of 

 that buff or size upon the blood, which is seen on the surface of 

 that which is drawn in the sensitive irritated fever; but the 

 blood, .as it cools, when it has been drawn into a basin, scarcely 



