ACTION OF REAGENTS UPON HUMAN BLOOD 13 



The mixing of human blood with the blood or serum of various animals 

 also has a similar action, probably owing to differences of density or 

 alkalinity. Tannic acid produces a peculiar effect (fig. 11, g) ; the 

 haemoglobin is discharged from the stroma, but is immediately altered 

 and precipitated, remaining adherent to the stroma in the form of a 

 round or irregular globule of a brownish tinge (haematin) . 



The structure of the colourless corpuscles is also brought out by 

 the action of these reagents. As the water reaches them their amoa- 

 boid movements cease ; they become swollen out into a globular form 

 by imbibition of fluid (fig. 12, i), and the granules within the proto- 



FIG. 1-2. 



1, first effect of the action of water upon a white blood-corpuscle ; 2, 3, white corpuscles 

 treated with dilute acetic acid ; n, nucleus. 



plasm can be seen to be in active Brownian motion. Their nuclei 

 also become' clear and globular, and are more conspicuous than before. 

 With the further action of the water, the corpuscle bursts and the 

 granules are set free. 



Acids have an entirely different action upon the white corpuscles. 

 Their nuclei become somewhat shrunken and very distinct (fig. 12, 

 2 and 3), and a granular precipitate is formed in the protoplasm around 

 the nucleus. At the same time, a part of the protoplasm generally 

 swells out so as to form a clear bleb -like expansion (an appearance 

 which often accompanies the death of the corpuscle from other 

 causes). 



