OF THE BLOOD. 217 



aniined them in many different animals; and the result of 

 these experiments was, that their size is different in different 

 animals (xcvn), as is seen in Plate V, where they are repre- 

 sented of the size they appeared to my eye, when viewed 

 through a lens of of an inch focus; which, allowing eight 

 inches to be the focal distance of the naked eye, magnifies the 

 diameter ] 84 times. 



It may not be improper to observe here, that the accurate 

 Leeuwenhoek, not having diluted the human blood or that of 

 quadrupeds so as to see these particles separate from each 

 other, was thence not qualified to describe them from Ms own 

 observation, as he has done those of fish and of frogs, and 

 suspecting a round figure was more fit for circulating in our 

 vessels, was thence led to suppose these particles spherical in 

 the human subject. But I shall hereafter be able to show 

 from his own words, that it is not his observations, but his 

 speculative opinions, or his theory, that differ from what I have 

 discovered by these experiments. 



In Plate V, it appears that of all the animals which I have 

 examined, the particles are larger in the fish called a skate; 

 next to a skate they are larger in a frog and a viper, and other 

 animals of this class ; they are somewhat smaller in the com- 

 mon fish, as the salmon, cod, and eel. In birds they are smaller 

 than in fish ; in the human subject smaller than in birds ; and 

 in some quadrupeds still smaller than in the human subject. 

 Leeuwenhoek, speaking of their size, says, he is confident the 

 red particles of the blood are no larger in a whale than in the 

 smallest fish. 1 And others have since his time said, they are 

 of the same size in all animals ; but it is evident from com- 

 paring their size as delineated in the above-mentioned plate, 

 that it differs considerably, and that they are not larger in the 

 largest animals; for we find that in an ox they are not so 

 large as in a man, and so far are they from being larger in 

 the whale than in the small fish, it appears probable, from 

 comparing their size, as delineated Plate V, fig. 2, from a por- 



1 Cons. Arcan. Nat. p. 220. 



(xcvir.) Concerning the shape and size of the corpuscles of man and 

 different animals, see Notes xcv and xcvin, and the Tables of Measure- 

 ments, Note ex viii*, pp. 236 et seq., at the end of this chapter. 



