88 The Microscope. 



monstrated. Now it is necessary to recollect, and I have very 

 often said it, that images of very finely striated structures can 

 by diifraction be modified to an extreme degree. Experiments 

 formerly made with Abbe's test have shown this most emphati- 

 cally. It is well, I think, not to allow one's self to become too 

 deeply puzzled b}'^ the ultimate form of these infinitely little de- 

 tails, for in such cases the microscope can no longer be a faithful 

 instrument since it shows us photographs of illusions. 



And each microscopist can see diff'erent things, according to 

 to the objective, the cover, the medium, the illumination that he 

 uses, and all those images about which we argue at random, may 

 each represent a thing that does not exist. 



WAVS • 

 AND MEANS 



DIFFERENTIAL STAINING OF HUMAN BLOOD 

 CORPUSCLES. 



F. A. ROGERS, M. D. 



THERE is scarcely anything which is easier to prepare for 

 microscopical examination, or which affords a prettier ob- 

 ject to look at when properly prepared, than a slide of dififeren- 

 tiated blood corpuscles. 



The article published by Dr Heitzmann in The Microscope 

 for May, 1890, is full of interest, and recently I have verified 

 some of the statements there presented in relation to the color- 

 less blood corpuscles. 



My object now, however, is not to discuss the differences 

 of the colorless corpuscles diagnostic of the general constitution 

 so well presented in that paper, but to show an easy way of 

 coloring a specimen of blood so that the red and the white cor- 

 puscles shall be properly differentiated, and when mounted shall 

 afford a slide which will delight anyone to study. 



The easiest and least objectionable way I have found by which 

 to obtain a specimen of blood is to proceed as follows. Having 

 cleaned the left fore-finger, take two or three turns tightly around 

 it just above the second joint with a pocket-handkerchief; then 



