356 LIQUID PARTS OF ANIMALS. 



bules gradually begin to subside to the bottom. He considered 

 them to be 25000 times smaller than a grain of sand.* Dr Jurin 

 afterwards pointed out a method of measuring their diameter, 

 and concluded it to amount in the globules of human blood to 

 T^i-5- of an inch.f They have since been measured by a variety 

 of micrometers. The following table, drawn up by Mr Le- 

 canu, will show the result of these different measurements.* 

 Size of globules in human blood. 



Sir Everard Home, TsW^ 1 f an 



Eller, 



Jurin, 



Rudolphi, 



Sprengel, 



Nodgkin, 



Lister, 



Senac, 



Tabor, 



Kater, 



Prevost and Dumas, 



Haller, 



Wollaston, 



Weber, 



[ 



^ 



, > 

 ) 



It has been observed that the size of the globules differs very 

 much in different animals. In the frog they are so large that 

 they are capable of being retained on a filter. The liquid which 

 passes through is yellow, while all the red colouring matter con- 

 stituting the globules remains on the filter. 



Various opinions have been advanced respecting the shape of 

 these globules. I pass by the opinion of Leewenhoek, which seems 

 whimsical. Father de Torre, who made use of very small sphe- 

 ricles of glass to examine them, considered them as very com- 

 pressed flat spheroids, or rings having a perforation in the centre. 

 Mr Hewson, whose microscopical observations on the blood were 

 first published in the Philosophical Transactions, || in order to 

 observe them easily, diluted the blood with fresh serum. In man, 

 he says, the globules of the blood are as flat as a shilling, and 



* Phil. Trans, ix. p. 121. f Ibid. 1723, Vol. xxxii. p. 341. 



f Etudes Chimiques sur le Sang Humain, p. 40. 



f Phil. Trans. 1765, p. 246. || Ibid. 773, p. 303. 



