MEDICAL WORK WITH MICROSCOPE 



sides bulge outwards and they may be described as 

 double convex. 



These little discs are known as red blood cor- 

 puscles. Their shape is some indication of the 

 animal to which they belong; those of man, as we 

 have seen, are circular and so are those of most 

 of the higher animals, except the camel tribe, which 

 has oval, red blood corpuscles. Birds, reptiles and 

 fishes have corpuscles agreeing in shape with those 

 of the camel. In size there is a great deal of 

 difference between the corpuscles of various animals ; 

 a member of the deer family has the smallest and 

 a creature related to our Newts, called Proteus, has 

 the largest. The size of the blood corpuscles bears 

 no relation to the size of the animal to which they 

 belong, those of the frog measure 1/1108 inch, or 

 nearly three times the size of the red blood cor- 

 puscles of man. Without much difficulty it should 

 be possible to obtain other samples of blood and the 

 red corpuscles should always be examined, needless 

 to say the blood should always be in a fresh con- 

 dition. In addition to the red corpuscles we may 

 notice a few smaller circular bodies, they are the 

 white corpuscles. If we have any difficulty in find- 

 ing them in our own blood, we can examine another 

 specimen of frog's blood, in which they are more 

 easily seen. It has been calculated that in a cubic 

 inch of blood from a healthy human being there 

 are eighty millions of red and a quarter of a million 

 of white blood corpuscles. Although there is such 

 an enormous difference in the sizes of red corpuscles 



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