THE MICROSCOPE. 1S9 



not adjusted for such a thin film as I was then using. In order to 

 improve the definition I turned the screw collar. As I turned, the 

 outline of the corpuscles grew sharper, but the net-work became more 

 indistinct. Finally, when the outline of the corpuscle came out 

 clear, I could see nothing of the net-work. Instead, the corpuscle 

 appeared to be covered with small nodules of unequal size, placed 

 at irregular intervals. 



I v/ent through nearly the same experience when, in place of 

 the -^0-, I put on the ^. At first, before the cover adjustment was 

 right, an indistinct appearance resembling a net-work was seen. But, 

 when the adjustment was such that the outline of the red corpuscles 

 in the field was sharpest, the same thing was seen as with the -j^g-, 

 only with greater clearness. I could, with the -y\, by toying with the 

 fine adjustment, focus the top of the nodules, while the remainder 

 of the corpuscle appeared in shadow; and then, by gently lowering 

 the glass, I could bring the valleys into view and leave the tops of 

 the nodules indistinct. By changing the direction of the light, I 

 could make the nodules cast shadows in first one direction and then 

 in another. With all the care I could use, I could get no other 

 appearance of a net-work than I have described as showing when 

 the adjustment of the glass was wrong. 



Having an abscess handy in my own person, I next examined 

 some fresh pus, first with the -^^ and then with the ^^, as I had done 

 ■with the blood. 



The pus showed very nearly the same as the white blood cor- 

 puscles, possibly more distinctly. Several of the pus corpuscles were 

 packed full of dancing granules. The movement of these granules 

 seemed to be independent of each other, and reminded me of small 

 animalcules imprisoned in a narrow space. By fixing my attention 

 on one of them and watching it for some time, I have seen it change 

 its location and travel nearly half way across the corpuscle before 

 escaping from view. 



I next put a drop of blood on a slide, and added to it a small 

 drop of a 40 per cent, solution of bichromate of potash. After an 

 hour or two, I examined the red corpuscles with the -jL and -j\ as I 

 had done with the fresh blood. Many of the corpuscles had lost 

 a good part of their color. With the color, they had also lost the 

 smooth surface which they usually possess in the fresh state. The 

 edges were finely crenated, the surfaces were thrown into nodules 



