172 ^I'e Jrt 0/ F A R R I E R Y 



L^ the Particles of tho Blood which are of the 

 next Size or Magnitude are required to be fepara- 

 ted, let the O.ifice of the Gland be fo big as to re- 

 ceive thofe fecond Particles, but fmall enough to 

 exclude all bigger Particles ; then thtfe fecond Par- 

 ticles, together with the firll or fmalleft, will enter 

 , the Gland : But becaufe the Liquor to be fecerned^ 

 or feparated is to confift only of the fecond Sort of 

 Particles that is, the fecond Sort of Particles onl/ 

 are to flow out at the Extremity of the Tube cr Ex- 

 cretory Dufl ; therefore we are to fuppofe that thi^ 

 Gland (which is only the Branch of an Artery, and 

 differs in nothing from a common Artery but in the 

 Narrownefs of its Chp.nnel,) has Branches which 

 are big enough to receive the fmallell Particles only, 

 and carry them off into the Veins ; fc thr:t as both 

 Sorts of Particles move together along the Gland, 

 the fmaileft Particles will pafs off through its Bran- 

 ches, and a Fluid confifting chiefly of the fecond 

 Sort of Particles, will arrive at the Excretory Du(5l 

 or Extremity of the convoluted Tube. 



Thus the' Number of Branches may be fo great, 

 as to draw cff moil of the fmallefl Particles before 

 the fecond Sort of Particles arrive at the Excretory 

 Dua ; fo that the Liquor to be fecernM or feparated 

 may confill of both thefe Sorts cf Particles mixed 

 too-ether in any Proportion, according to the Num- 

 ber of Branches. 



If a Fluid confining of a third Sort of Particles 

 larger than anv of the former, is to befecern'd, the 

 OrTiice of the Gland mull be jull big enough to ad- 

 mit fuch Particles, and none bigger ; and the Bran- 

 ches of the Gland mull be fmall enough to exclude 

 the biggell Particles and big enovgh to receive the 

 leffer : ^And according as the Number cf Branches 

 is either greater or fmaller, the Fluid which runs 

 out at the Excretory Dufts will confill either of the 

 hrgeft Particles, or of all together mixed in any 

 Proportion. 



