52 The Microscope. 



more and more widely accepted as one of the histological 

 properties of the cell. In the entire domain of animal 

 histolog}^ there is hardly anything so interesting, and 

 indeed so readity seen and demonstrated, as the reticulated 

 structure of the protoplasm forming the red blood corpuscles of 

 the vertebrates, especially of man himself. With the proper 

 high power objective, ever}^ reader, medical or otherwise, with 

 two hours of leisure time, can himself see this structure in his 

 own blood and can show it to others. 



All that is needed in addition to the proper objective is a 

 solution of the bichromate of potassium. Writers on the subject 

 speak of a fifty per cent, aqueous solution, a chemical absurdity 

 because a chemical impossibility. The salt dissolves in the pro- 

 portion of one part to ten of water ; a ten per cent, solution is 

 therefore the strongest that can be made. Even this, for the 

 present purpose, is needlessly concentrated. A five per cent, 

 solution is better, and this may be prepared b^^ dissolving 

 twenty-three grains of the potassium salt in a fluid-ounce of 

 water. When filtered it is ready for use. 



A glass slip without a cell should be used. Oil the margin of 

 a thin cover-glass, to prevent evaporation, and on the slip place 

 a small drop of the potassium bichromate solution. Prick the 

 finger and touch the cover-glass to the blood. A small drop is 

 needed, the smaller the better. Quickly invert the blood into 

 the potassium solution and place the slide on the stage as 

 speedil}^ as possible. Although one's movements may be rapid, 

 it is almost impossible to get ready to look through the micro- 

 scope before alterations have begun to take place in the red cor- 

 puscles. And here the blood of the same person will act diff'er- 

 ently at diflferent times. The red corpuscles will always become 

 crenated, irregularl}^ constricted and distorted, while the sur- 

 face and the margins will be strangely knobbed. The soft sub- 

 stance will protrude into rounded, knob-like projections almost 

 as soon as the potassium touches the corpuscle. In such cases 

 the knobs are finally withdrawn and the surface again becomes 

 smooth, the internal changes then appearing in a short time. 

 On other occasions, with the same blood, the corpuscles will 

 extrude rounded masses apparently connected with the globule 

 by only tlie slightest tenure ; the knob-like protrusions will 

 elongate into delicate, often moniliform threads, or thickened 



