1 1 2 British UredinecE and Ustilao-inecE. 



moisture is contained in the cell itself; all that is required 

 is to place them under a bell-glass to keep them free from 

 dust. The disadvantage of this mode of culture is, that 

 all spores will not germinate normally unless they get a 

 supply of free air. To obviate this hindrance, the glass 

 cover may be fixed to the cell with three tiny fragments of 

 wax. These cells may be readily constructed with lead 

 tubing ; an ordinary piece of gas-piping, cut into suit- 

 able lengths with a knife, and the ends smoothed on a 

 whetstone, will answer all the requirements of the case. 



The germination of the spores in ndhrlds2ing, however, 

 requires more care. The nahrlosung is prepared by boiling 

 fresh horse-dung in pure water, and filtering first through 



Fig. 12. — One of Brefeld's " kniiiiner" for nahrlosung cultures. It consists of a glass 

 tube open at both ends ; in the middle a bulb has been blown which has been compressed 

 laterally, so that its sides are parallel to each other, or nearly so. When in use the two open 

 ends of the tube are closed with cotton wool. 



coarse filtering-paper, then through fine ; then boiling again 

 for a short time in a flask, the mouth of which is closed, 

 while the steam is issuing from it, by a firm plug of cotton 

 wool. After three or four hours the flask is again boiled 

 for a short time. To sterilize the fluid this boiling requires 

 to be repeated several times, carefully closing the mouth ot 

 the flask each time with a plug of cotton wool. The spores 

 to be germinated are put in a small quantity of sterilized 

 nahrlosung, and the process watched tJi camera. The little 

 apparatus necessary consists of a glass tube about eight or 

 ten inches long, open at both ends ; in the middle of this 

 tube a bulb has been blown, the sides of which have been 

 compressed laterally (Fig. 12), so that they are flat and 

 parallel to each other. Before using, the apparatus {kavimer) 



