Sporc-Cnlture. 



I I r 



place the spores in water, and they will germinate at once — 

 for example, U. segetuin, longissima, etc. ; but some require 

 a longer period of immersion, e.g. T. tritici, which will not 

 germinate till after being several days in water. The 

 germination of the Tilletia spores can also be conducted in 

 a hanging-drop culture in the following manner : — A piece 

 of glass tube, about half an inch (12 mm.) in diameter and 

 about three-quarters of an inch (18 mm.) long, is cemented 

 on an ordinary glass slide, so as to form a deep cell (Fig. 10). 



Fig. 10.— Deep cell for hanging-drop cultures, xuade by cementing a piece of glass or lead 

 tube upon an ordinary glass slide. 



Into this is placed a small quantity of water. The drop 

 containing the spores to be germinated is placed on the 

 centre of a circular cover-gla.ss, which will fit the top of the 

 cell (Fig. 11). If the upper edge of the tube which forms 



Fig. II. — Hanging-drop culture, seen in section. 



the cell be oiled, no air can get into the culture, and the 

 germination can be watched for months, as the hanging- 

 drop will not evaporate, because the water placed in the 

 bottom of the cell keeps the atmosphere saturated, and 

 any loss which it may sustain from evaporation is made 

 up from the water at the bottom of the cell. 



There is no need to keep these sealed hanging-drop 

 cultures in a moist atmosphere, because the necessary 



