Thermal Death-point of Monad Germs. By W. H. DaUinger. 7 



a hollow bulb intended as a reservoir for the infusion containing 

 any organism we may desire to study. The infusion is put in 

 through the funnel and tube B. The bulb A opens into a 

 tube D on the opposite side, and this tube terminates in a delicate 

 closed and flattened cell C. In a microscopical point of view 

 this cell is the most important part of the apparatus. It is a 

 flattened bulb, and its upper and under walls are films of glass, 



Fig. 3. 



varying in different pieces of the apparatus from the ^\ to the 

 ^^^ of an inch in thickness ; and the space between these walls 

 may vary from the ^5^^ to the tw of an inch in depth. We 

 thus have a perfect cell, completely closed, the contents of which 

 can readily be studied with the aid of the most powerful lenses. 

 The walls of the cell are of course not as absolutely even and smooth 



Fig. 4. 



=Q 



as the thin '' covering glass " usually employed with high-power 

 lenses ; but it is in the majority of cases beautifully level and clear, 

 when the manner of its production is remembered. Of course, 1 

 should never have employed those cells for the purpose of dis- 

 covering delicate and unknown details ; but they answer admirably 

 for determining the presence or absence of phenomena, the nature 

 of which is well known beforehand. 



