Chap. II.] 



BLOOD. 



it 



about -j^Vo of an inch on the broad, and ^ov of an 



inch on the narrow side. But there are always 



corpuscles present which are much smaller by about 



one-third to one-half 



than the others. In >^ * f\ 



normal blood these W 



small red corpuscles 



are scarce ; in certain 



abnormal conditions, 



especially anaemia, or 



scarcity of blood, they 



are more numerous. 



According to Gulliver, Welcker, and others, the 

 following are the measurements of the sizes of red 

 blood corpuscles of various vertebrates : man, ^Vo > 

 dog, Vo ; cat > TWO J shee P> TtW ; elephant, ^^ ; 

 horse, ^Vo- ; musk deer > T<mnr ; pigeon, ^Vr '> toad > 

 newt, i ; proteus, ^ ; pike, ^Vo ; shark > 



A B 



Fig. 6. Various kinds of Eed Blood 

 Corpuscles. 



A, Two human, one seen from the broad, 

 the other from the narrow side ; B, a red 

 corpuscle of the camel ; c, two red corpus- 

 cles of the frog, one seen from the broad, 

 the other from the narrow side. 



11. In a microscopic specimen of fresh unaltered blood 

 (Fig. 7) the red blood corpuscles form peculiar shorter 



or longer rolls, like so 

 many coins, becoming 

 adherent to one another 

 by their broad surfaces. 

 Under various condi- 

 tions such as when 

 isolated, or when blood 

 is diluted with saline 

 solution or solutions of 

 other salts (sulphate of 

 sodium or magnesium) 

 the corpuscles lose 

 their smooth circular 

 outline, shrinking and 

 In a further stage of this 



Fig. 7. Human Blood, fresh. 



A, Rouleaux of red corpuscles ; B, isolated 

 red corpuscle seen in profile ; c, isolated 

 red corpuscle seen from its broad sur- 

 face ; D, white corpuscles. 



becoming crenate (Fig. 8, A). 



process of shrinking they lose their discoid form, and 



