acS CIRCULATORY Sect. XXlII. 2. 1. 



than that of a dog, and eight times greater than that of a fallow 

 dee. 



The power of abforption in the animal fyftem exerts a force 

 fuperior to that of the heart, though perhaps with lefs velocity ; 

 2nd thus removes all difficulty of accounting for the circulation 

 in the veins and abforbents ; and confequenrly of the circulation 

 in the aortal arteries of fifh, and in the vena portaru m, or the 

 bile-fecreting artery of the liver of quadrupeds. 



II. 1. The glandular fyftem of veffels may be divided into thofe, 

 which take fome fluid from the circulation ; and thofe, which 

 give fomething to it. Thofe, which take their fluid from the cir- 

 culation, are the various glands, by which the tears, bile, urine, 

 perfpiration, and many other fecretions are produced •, thefe 

 glands probably con lift of a mouth to fele£t, a belly to digeft, and 

 an excretory aperture to emit their appropriated fluids ; the 

 blood is coaveyed by the power of the heart and arteries to the 

 mouths of thefe glands, it is there taken up by the living power 

 of the gland, and carried forwards to its belly, and excretory ap- 

 erture, where a part is feparated, and the remainder abforbed 

 by the veins for further purpofes. 



Some of thefe glands arc furnifhed with long convoluted necks 

 or tubes, as the feminal ones, which are curioufly fcen when 

 injected with quickfilver. Others feem to confifl of fhorter 

 tubes, as that great congeries of glands, which conftitute the liver, 

 and thofe of the kidneys. Some have their excretory apertures' 

 opening into refervoirs, as the urinary and gall-bladders. And 

 others on the external body, as thofe which fecrete the tears, 

 and perfpirable matter. 



Another great fyftem of glands, which have very (hort necks, 

 are the capillary veffels ; by which the infcnflble perfpiration is 

 fecreted on the fkin ; and the mucus of various confiftenceSj 

 which lubricates the interftices of the cellular membrane, of the 

 mufcular fibres, and of all the larger cavities of the body. From 

 the want of a long convolution of veffels fome have doubted, 

 whether thefe capillaries mould be confidered as glands and 

 have been led to conclude, that the perfpirable matter rather ex- 

 uded than was fecreted. But the fluid of perfpiration is not Am- 

 ple water, though that part of it, which exhales into the air may 

 be fuch ; for there is another part of it, which in a (late of health 

 is abforbed again ; but which, when the abforbents are difeafed, 

 remains on the furface of the (kin, in the form of fcurf, or indu- 

 rated mucus. Another thing, which (hews their fimihtude to 

 other glands, is their fenfibility to certain affections of the mind 5 

 ss is (czn in the deeper colour of the fkin in the blufh of iliame, 



the greater paleneft of it from fear. 



III. Another 



