MEDICAL WORK WITH MICROSCOPE 



two samples of blood, one from a perfectly healthy 

 subject and one from a so-called bloodless subject 

 we shall probably not be able to detect any differ- 

 ence between the two, but the experienced medical 

 man will soon see that one sample has too few red 

 blood corpuscles. 



An unhealthy state of the blood if often indicated 

 by the shape of the blood crystals. Let us see how 

 we may obtain some of these crystals. If we add a 

 drop of ether to our drop of blood upon the slide, and 

 wait a few moments till the ether has evaporated, 

 we shall notice when we examine our object again, 

 under a high magnification, that a number of 

 prismatic crystals have formed, especially towards 

 the edges of the slide. Now in certain diseases of 

 the blood, these crystals are no longer formed in 

 their usual shape, thus pointing out to the medical 

 man that something is amiss. Again there are many 

 blood parasites just as there are external parasites 

 of man. In the disease known as malaria, very 

 small parasites are introduced into the blood by 

 mosquitoes. Each of these little parasites enters 

 a red blood corpuscle, divides up into many smaller 

 individuals, causes the corpuscles to burst, then 

 each little parasite attacks more corpuscles. Some 

 of these little bodies are sucked up, along with the 

 blood of malaria patients, by other mosquitoes and, 

 if the insects are of the particular kind which spread 

 malaria, the parasites complete their development 

 within the mosquito. Patients suffering from that 

 terrible African malady known as sleeping sickness, 



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