268 The Microscope. 



6. Action of Reagents. — Water has the effect of changing 

 the red globules to a spherical form. Many times the central 

 depression of one side will disappear before it does on the other, 

 giving them a peculiar cup-shaped form; finally' the water dis- 

 solves out the coloring matter, the corpuscles become paler and 

 paler until after a time they are totally disintegrated. Acetic 

 acid brings these changes with great rapidity. The alkalies are 

 very active in dissolving their whole substance. A 1 p. c. solu- 

 tion of salt will cause the red corpuscles to assume the crenate 

 or horse-chestnut form, in which their surface is covered with 

 minute spinous projections. This same appearance is seen in 

 corpuscles that have been exposed to the air a short time. This 

 may be due to the loss of carbonic acid by the plasma, the cor- 

 puscles then loose carbonic acid themselves and this is followed 

 by a shrinking of part of the stroma. Tannic acid, in a 2 p. c. 

 solution causes the haemoglobin to collect at the periphery in 

 the form of one or more small refractive buds. 



These peculiar buds are explained as 



^ggp \§j/ C*% T~\ follows : The tannic acid, like many other 



A / - N ^ B ° d reagents, causes the coloring matter to 



v-^ 3|!p separate from the stroma, as the separated 



E coloring matter passes out of the corpuscle 



FIG. 2— Human red blood- ... i^iiii.1 •^•4.1 



corpuscles, a, when it becomes coagulated by the acid, in the 



slightly within the fo- , . , . . , ,. 



cus; b, when viewed form of round, granular-looking bodies. 



slightly without the fo- . 



cus; c, e, after the ad- All reagents are best applied by placing a 



dition of water: D, after D rr 



S&Tf!2SSt ttiSSBi- sraa11 P iece of blotting paper to one edge 



tion of salt solution, x Qf ^ CQyQV ^ a drQp of fche reagent to 



the opposite edge. The reagent will be readily drawn under 

 the cover and thus the specimens will be " irrigated/' 



THE WHITE CORPUSCLES. 



These bodies never enter into the rouleaux as do the red. 

 They do not roll about so readily. They are larger than the 

 red. By " irrigating" the specimen the red corpuscles can be 

 all washed away, while the white will remain. They appear as 

 highly transparent bodies, dotted with minute granules. In 

 each corpuscle there is one nucleus ; many times two or three 

 nuclei. 



