346 ESSAYS anp OBSERVATIONS 
fluids alfo begin to flagnate firft in the 
fmaller and afterwards in the larger vef= 
fels *; while the heart becoming gradu- 
ally lefs fenfible of the /#jmulus of the 
blood with which it is diftended, con- 
tratts more feebly and at greater inter= 
vals, till at laft it ceafes from motion al- 
together? 
ART. 
* This my worthy Colleague Dr Alfton obferved witht 
a microfcope in frogs into whofe ftomach he had convey- 
ed a few drops of a folution of opium in water. Vid, Me- 
dical Eflays, vol. 5. part 1. art xii. And indeed, the 
great diftenfion of the heart and its auricle in frogs killed 
with opium (N° 5. compared with No 3. 6, and 10. above) 
indicates a more than ordinary refiftance to the blood’s 
motion in the arteries, as well as a lefs degree of irritas 
bility in the heart, Further, is not the flow, full pulfe, 
and dry parched mouth in thofe who have got an over- 
dofe of opium, owing, partly, to the flower motion of the 
fluids in the fmall arteries and fecretory veflels of the 
glands? Though it muft be confefled, that the drynefs 
of the mouth may be in fome meafure owing to the per~ 
‘fpiration being greatly increafed by the opium, 
