44 



SCIENCE PRIMERS. 



[§iv. 



dimpled in the middle, something like certain kinds 

 of biscuit. When you see one by itself it looks a 

 little yellow in colour, that is all ; but when you see 

 them in a lump, the lump is clearly red. Remember 

 how small they are : three thousand of them put flat 

 in a line, edge to edge, like a row of draughts, would 

 just about stretch across one inch. All the redness 

 there is in blood belongs to them. When you see 

 one of them, you see so little of the redness that it 

 seems yellow. If you were to put a drop of blood 

 into a tumbler of water, the water would not be 

 stained red, but only just turned of a yellowish tint, 

 so little redness would be given to it by the drop of 

 blood. In the same way a very very thin slice of 

 cuixant jelly would look yellowish, not red. 



These red corpuscles are not hard solid things, but 

 delicate and soft, very tender, very easily broken to 

 pieces, more like the tiniest lumps of red jelly than 

 anything else, and yet made so as to bear all the 

 squeezing which they get as they are driven round 

 and round the body. 



Besides these red corpuscles, you may see if you 

 ^ ittentively other little bodies, just a little 

 ^ger than the red corpuscles, not coloured at 

 all, and not circular and flat, but quite round 

 like a ball (Fig. 4, a, F, G). That is to say, these are 

 very often quite round, only they have a curious trick 

 of changing their form. Imagine you were looking 

 at a suet dumpling so small that about two thousand 

 five hundred of them could be placed side by side in 

 the length of one inch — and suppose the round dump- 

 ling while you were looking at it gradually changed 

 into the shape of a three-cornered tart, and then into 



