Sect. III.] Theonj and Practice of Phijsic. 3 1 9 



ticdl work, with all their imperfections, contain 

 perhaps more medical learning than any book ex- 

 tant of the same size. 



The most prominent feature in the Boerhaaviun 

 system is the attempt to explain the phenomena 

 of the animal economy, whether in healtli or disease, 

 upon mechanical principles. Under the impres- 

 sion of such opinions he considered the body ehirfly 

 as an hydraulic machine, composed of a conic, elas- 

 tic, inflected canal, divided into similar less canals, 

 all proceeding fron the same trunk; which, beinpr at 

 last collected into a retiform contexture, nuitually 

 open into each other, and send olV two orders of 

 vessels, lymphatics and veins, the former terminat- 

 ing in different cavities, the latter in the heart; 

 that these tubes are destined for the conveyance of 

 the animal fluids, in the circulation of which he 

 <?upposed life to consist, and on the free and undis- 

 turbed motion of which he judged health to depend. 

 lie therefore believed obstruction to be the proxi- 

 mate cause of most diseases; and this obstruction 

 he supposed to be produced either by a constriction 

 of the vessels, or by a lentor in the blood. 



In Boerhaave's doctrine of obstruct ioUy which is 

 fundamental in his system, he makes an important 

 use of Leuwenhoeck's supposed discoveries c:on- 

 cerning the blood. That, eminent microscopical 

 investigator had imagined that iio found each glo- 

 bule of red blood composed of six serous globules, 

 the serous of six lymphatic globules, the lym- 

 phatic of six other globules still fnier, and so on m 

 a similar progression till these particles were dnm- 

 nished down to the finest and most subtde of all, 

 namelv, the nervous fluid. According to l^o.r- 



