244 C. M. WKNYOX. 



use of this medium, and one which will allow observations to 

 be made with high powers, is the following : A long cover- 

 glass (l-i inches) is taken and carefully cleaned. On a clean 

 slide ridges of Czokor's wax, first recommended to me by 

 Professor Mincliin, are so arranged, about an eighth of an inch 

 high, that the cover-glass will form tlie lid of a box. Some 

 of the medium is melted by placing the test-tube in boiling 

 water, and a small drop of this is allowed to fall on to the 

 cover glass, which is lying on the top of the hot-water oven. 

 By careful tilting of the cover-glass the melted medium will 

 form a very thin layer over the cover-glass, which is then 

 removed so that the medium may solidify. The surface of the 

 medium is then inoculated with a small quantity of material 

 from a previous culture and the cover-glass inverted on the 

 wax ridges. By means of a hot wire and more wax the whole 

 Tuay be completely sealed up. It is most essential that not 

 the smallest opening be left, or it will be found that the 

 medium will quickly dry and the culture end. 



In this way it is easy to follow the multiplication of the 

 Hagellates with the ^in, objective, and if the film of medium 

 has been made sufficiently thin the oil-immersion may be 

 employed. 



In every case where the flagellates grow in the solid 

 medium their chief nourishment seems to be the numerous 

 bacteria that grow at the same time. 



For studying the flagellates in the fixed and stained con- 

 dition the cover-glass method has been mostly used. Some 

 of the liquid medium or some of the culture scraped from 

 the surface of the agar is spread on a clean cover-glass, and 

 without allowing it to dry it is dropped, film side down, on to 

 the surface of some fixing fluid. Another method of obtain- 

 incr a film from the agar cultures is this: A cover-glass is 

 dropped on to the surface of the agar culture in a Petri dish. 

 It is gently pressed down till its sui-face is seen to have 

 touched the culture. On raising it with a needle it will be 

 found that a layer of the culture is adherent to the cover- 

 glass, and it may be fixed as before. 



