THE STORY OP THE HEART 



63 



perceiving the clear fluid in which the corpuscles 

 float. 



THE BLOOD CORPUSCLES. Two kinds of corpuscles , 

 it has been noted, exist in the blood, the red and the 

 white. The red (Fig 18) are far more numerous than 

 the white, the proportion on the average being 1 white 

 to 600 or 700 red, although after meals the proportion 

 of white corpuscles appears to be increased, but soon 

 apparently lessened down to the amount just stated. 

 The size of a red corpuscle may be set down on the 

 average at about 

 the 1 -3,200th of an 

 inch in diameter; 

 a white corpuscle 

 is somewhat lar- 

 ger, about the 

 1 -2,500th of an inch 

 across. Very im- 

 portant differ- 

 ences are to be 

 noted between the 

 white and red cor- 

 puscles, not mere- 

 ly in respect of 

 their nature, but 

 also with reference to the duties they perform. The 

 red corpuscles contain a substance called hcemoglo- 

 bin which contains a very appreciable amount of 

 iron. This substance may be regarded as therefore 

 giving colour to the blood, and the value of iron ad- 

 ministered as a blood tonic, therefore finds in the 

 fact just related full justification. The haemoglobin 

 of the red blood corpuscles readily combines with 

 oxygen gas, the all-important element we breathe in 

 from the atmosphere, this gas being readily parted 



Fig. 18. DIFFERENT RED BLOOD 

 CORPUSCLES. 



(a) those of man ; (6) those of a frog 



oval and nucleated, that is, having a 



central particle. 



