84 



BIOLOGY AND ITS MAKERS 



emy of Sciences, of which he was elected a corresponding 

 member in 1697, got twenty-seven; but the hon's share 

 fell to the young Royal Society of London, which in fifty 

 years — 1673-1723 — received 375 letters and papers." " The 

 works themselves, except that they lie in the domain of 

 natural history, are disconnected and appear in no order 

 of systematized study. The philosopher was led by what 

 transpired at any moment to lead him." 



The Capillary Circulation. — In ^686 he obser ved the 

 minute CLxcula.tion of-the^bleed , and demimsLmled-the ca^iil- 

 Jaty connection between arteries and veins, thus forging the 



final link in the chain of 

 observation showing the 

 relation between these 

 blood-vessels. This v.as 

 perhaps his most important 

 observation for its bcarin<2j 

 on physiology. It must be 

 remembered that Harvey 

 had nat-actiiall^L_seen the 

 circulation of — tfee_blood, 

 which he announced in 

 1628. He assumed gn en- 

 tirely sufficicni-grounds the 

 existence of a cqnoplete cir- 

 culation, but t here w as 



^'L^^^T^H^ Capillary Circula- ..^anting in his scheme the 

 tion. (After Leeuwenhoek.) ^ 



direct-Qcubi-pniof of the 

 passage of blood from arteries tojyeins. lliis was sjjjiplied 

 b)L Le£jj Av en li oxik . Fig. 20^ shows one of his sketches of the 

 capillary circulation. In his efforts to see the circulation 

 he tried various animals; the comb of the young cock, the 

 ears of white rabbits, the membraneous wing of the bat were 

 progressively examined. The next advance came when he 



