112 British Uredinee and Ustilaginee. 
moisture is contained in the cell itself; all that is require: 
is to place them under a bell-glass to keep them free fron 
dust. The disadvantage of this mode of culture is, tha 
all spores will not germinate normally unless they get ; 
supply of free air. To obviate this hindrance, the glas. 
cover may be fixed to the cell with three tiny fragments o 
wax. These cells may be readily constructed with leac 
tubing; an ordinary piece of gas-piping, cut into suit 
able lengths with a knife, and the ends smoothed on < 
whetstone, will answer all the requirements of the case. 
The germination of the spores in xa&hrlisung, however 
requires more care. The nahrlésung is prepared by boiling 
fresh horse-dung in pure water, and filtering first through 
Fig. 12.—One of Brefeld’s ‘‘ésmer” for nahrlésung cultures. It consists of a glass 
Haceralby seadige smatioters peoalctimeaciatoer aunearig ie Mikes ia uaee eee 
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 
nahrlésung, and the process watched zz camerd. 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 (Aammer) 
