

HISTOLOGICAL DEMONSTRATIONS. 57 



becomes transparent, and the nuclei very distinct From 

 three to five nuclei are usually revealed in the large cor- 

 puscles. The amoeboid motion is arrested by the acid. 



72. Effect of Dilute Alcohol. Dilute alcohol (rectified spirit 

 I part, 'water 2 parts) is a useful re- agent for the blood corpuscles 

 (Ranvier). Under its influence the frog or newt's coloured corpuscle, 

 and also its nucleus, become swollen, and a nucleolus is revealed. The 

 nuclei of the colourless corpuscles become evident, and one or more 

 very delicate clear blebs grow from the periphery of the white cor- 

 puscle, apparently consisting of some colloid substance, into which 

 endosmose takes place rapidly. 



73. Effect of Water. Make a preparation of the 

 same blood, and add water as described in 71, d. The 

 coloured corpuscles become more or less globular, owing 

 to endosmose, and they lose colour owing to diffusion of 

 their pigment into the surrounding fluid. 



74. Effect of Strong Syrup. Place a drop of the 

 same blood on a slide, add a drop of strong syrup, and 

 quickly mingle the two with the point of a needle, then 

 apply the cover-glass. The coloured corpuscles shrivel, 

 owing to exosmose. It is to be observed that some of the 

 coloured corpuscles shrivel rapidly, while others undergo 

 no change for a considerable time. Possibly the latter are 

 older corpuscles and have thicker envelopes. 



75. Effect of Magenta. To a drop of the same 

 blood add a drop of the special magenta fluid used for 

 staining blood corpuscles ( 324, b). Mix the two with the 

 point of a needle, and then cover. The nuclei of coloured 

 and colourless corpuscles become brilliantly stained. The 

 magenta fluid here employed contains a quantity of glycerine 

 sufficient to render its specific gravity similar to that of the 

 blood, with a view to prevent the swelling of the coloured 

 corpuscles. If the coloration take place slowly, however, 

 a drop of the ordinary watery magenta fluid may be added 

 to facilitate the penetration of the corpuscle by the dye. 



76. Effect of Tannic Acid. Dissolve 5 decigrammes 

 tannic acid in H3CC hot water, and allow it to become 

 cold. Place a drop of the same blood on a slide, and 

 cover. Bring into focus the corpuscles near the right 

 margin of the cover-glass, and place as quickly as possible 



