ACTION OF REAGENTS ON THE BLOOD. 37 



whilst under observation a small drop of the reagent 

 (which should as a rule be freshly prepared) is al- 

 lowed to come into contact with the edge of the 

 cover-glass. Some of the fluid flows under this and 

 mixes with the drop of blood ; the current produced 

 by it at first drives the corpuscles before it, but they 

 soon become stationary, and then the part of the 

 preparation should be selected for observation where 

 the reagent is gradually diffusing itself amongst the 

 corpuscles. In this way every stage in its action 

 may readily be studied. 



Preparation 3. Action of water. When a 

 drop of distilled water is applied in the manner 

 above described, the first efleet is seen to be that the 

 red corpuscles begin to lose their discoid form, first 

 one of their sides becoming bulged out, so that they 

 are cup-shaped, and then the other side, so that they 

 are now completely globular, as may be seen when 

 they roll over. Meanwhile the haemoglobin is being 

 dissolved out of the corpuscles by the water, so that 

 they are soon quite colorless and hardly to be de- 

 tected in the now reddish fluid Some seem to offer 

 greater resistance to the action of the water (and 

 indeed of most reagents) and to retain their coloring 

 matter longer than others. 



The white corpuscles are also soon affected. They 

 cease their amoaboid movements, and begin to swell 

 up by imbibition of fluid, whilst at the same time 

 with a high power the granules in their interior 

 may be seen to exhibit the dancing movement which 

 is characteristic of minute particles floating in 

 liquid. Often the corpuscles present clear bulgings 

 at their circumference, or their substance may ap- 

 pear to burst at one point and become diffused in 

 the water. As they swell and become clearer, one, 

 two, or more small round nuclei generally come into 

 view, and soon these also become swollen, and with 

 the rest of the corpuscles eventually disintegrate, 

 nothing being left but a few granules. 



Water is thus proved to have a characteristic ac- 

 4 



