BL( JOD-COEPUSCLES 



1035 



double convex, the dark spot disappears ; whilst, on the other hand, 

 it is made more evident when the concavity is increased by the 

 partial shrinkage of the corpuscles, which may be brought about 

 by treating them with fluids of greater density than their own sub- 

 stance. When floating in a sufficiently thick stratum of blood 

 drawn from the body, and placed under a cover-glass, the red 

 corpuscles show a marked tendency to approach one another, adher- 

 ing by their discoidal surfaces so as to present th<> aspect of a pile 

 of coins ; or, if the stratum be too thin to admit of this, partially 

 overlapping, or simply adhering by their edges, which then become 

 polygonal instead of circular. The size of the red corpuscles is not 

 altogether uniform in the same blood ; thus it varies in that of man 

 from about the q. 7 , 1 , TT) -th to the -., sVoith of an inch. But we generally find 

 lliat there is an average size, which is pretty constantly maintained 

 among the different individuals of the same species ; that of man may 



be stated at about 



of an inch. 



The following table l exhibits 



Man . 

 Dog . 

 Whale 

 Elephant 

 Mouse 



Golden eagle 



Owl 



Crow 



Blue-tit . 



Parrot 



Turtle . 

 Crocodile 

 Green lizard 

 Slow-worm 

 Viper 



Perch 



Carp 



Gold-fish 



MAMMALS 



1-3200 Camel . . 1-3254, 1-5921 



1-3542 l Llama . . 1-3361, 1-6294 



1-3099 Javan chevrotain . 1-12325 



1-2745 ' Caucasian goat . 1-7045 



1-3814 ! Two-toed sloth 1-2865 



BIRDS 



1-1812, 1-3832 

 1-1830, 1-3400 

 1-1961, 1-4000 

 1-2313, 1-4128 

 1 INKS, 1-4000 



Ostrich . 



Cassowary 



Heron 



Fowl 



Gull 



REPTILES AXD BATRACIIM 



1-1231, 1-1882 

 1-1231, 1-2286 

 1-1555, 1-271:; 

 1-1178, 1-2666 

 1-1274, 1-1800 



Frog 



\V;iter-newt 

 Siren 

 Proteus . 

 Arnphiuma 



FISHES 



1-2099, 1-2824 Pike 

 1-2142, 1-3429 Eel. 

 1-1777, 1-2&24 Gymnotus 



1-1649, 1-3000 

 1-1455, 1-2800 

 1-1913, 1-3491 

 1-2102 1-3466 

 1-2097, 1-4000 



1-1108, 1-1S21 



1-8014, 1-1246 



1-420, 1-760 



1-400, 1-727 



1-345, 1-561 



1-2000, 1-3555 

 1-1745, 1-2842 

 1-1745, 1-2599 



the average dimensions of some of the most interesting examples of 

 the red corpuscles in the four classes of vertebrated animals, expressed 

 in fractions of an inch. Where two measurements are given they 

 are the long and the short diameters of the same corpuscles. (See a 1 .-.<> 

 fig. 768.) Thus it appears that the smallest red corpuscles known 

 are those of the Javan chevrotain (Tragnlus javanicus), whilst the 

 are those of that curious group of Batrachia (frog tribe) which 



1 These measurements are chiefly selected from those given by Mr. Gulliver in 

 his edition of Hewson's W'vrks, p. '2:>(5 ft seq. 



