FIG. 131. 



Red blood- cells of man and of am- 

 phiuma, magnified to the same extent 

 to show the size of the human cor- 

 puscles in comparison with that of the 

 largest known blood-cell. 



THE CIRCULATORY SYSTEM. 



are more e_nitive to changes in environment or to the effects of 

 reagents than are the cells of the blood. An appreciation of the 

 alterations referable to external causes is important as guarding 

 against unwarranted conclusions as to the existence of pathological 

 conditions, since not infrequently ap- 

 pearances which lead the tyro to infer 

 disease may be ascribed tcPThfluences 

 acting on the corpuscles outside the 

 body. 



If fresh blood be exposed to a current 

 of air, subjected to unduejDressure or to 

 other disturbing influences, alterations of 

 the corpuscles at once take place. One 

 of the most common distortions affects 

 the exterior of the red corpuscles, and 

 results in the formation of a number 

 of minute projections, or spines, pro- 

 ducing a condition known as crenation. 



Saline Solutions. The~application of a weak saline solution or 

 of urine is attended with similar effect ; if the strength of the reagent 

 be gradually increased, a corresponding progressive degree in the 

 distortion is observed, until, finally, upon the 

 addition of a concentrated brine, a shrivelled, 

 shapeless mass replaces the former discoidal 

 red corpuscle. The reaction is less marked 

 upon the colorless cells, weak salines pro- 

 ducing no perceptible change, while a slight 

 shrinkage is noticeable after the stronger 

 solutions. 



Water. Upon the application of water 

 the colored cells swell up, lose the discoidal 

 form, and become spherical, and at the same 

 time part with their coloring matter, the 

 haemoglobin ; the latter, being dissolved, 

 leaves the bleached and colorless stroma to 

 form the ' ' ghost. ' ' That the red corpuscles 

 are not destroyed by the water, as sometimes 

 stated, may be demonstrated by the addition 

 of a suitable aniline dye, when the presence 

 of the bleached corpuscles is made evident by 

 the colored rings which mark their outlines. 



The action of water upon the living color - 

 less blood-cells is somewhat different. 

 These corpuscles cease their amoeboid movements, retract their 



FIG. 132. 



Q 



Reactions of human blood- 

 cells with various reagents: 

 A, effect of treatment with 

 water upon the white (iv) and 

 the colored cell (r); B, red 

 cells after the addition of saline 

 solutions, crenation following 

 the application of weak solu- 

 tions, great shrinking and dis- 

 tortion (j) succeeding the 

 action of the concentrated 

 reagent; C, action of dilute 

 acetic acid on the colorless 

 cell (w) and on the red cor- 

 puscle (r) ; D, red blood-cell 

 after the addition of one-per- 

 cent, solution of tannic acid. 



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