34 
HOLTERMANN : FUNGUS CULTURES 
coverslips were kept germ-free in the same way. Micro- 
scope slide glasses were taken out of the alcohol with forceps 
and at once passed through a flame ; if they are then laid 
upon one another in a sterilized vessel they can be pre- 
served for a long time. Flasks, after careful washing, 
were thoroughly washed out with alcohol and stood bottom 
upward, but in such a way that the alcohol could evaporate, 
and afterwards closed with a plug of wadding, which had 
been previously freed from germs with a solution of corro- 
sive sublimate in alcohol (1 part in 1,000). Other means of 
disinfection for glasses and instruments are not to be recom- 
mended ; I must particularly utter a warning against the 
use of carbolic acid, corrosive sublimate, and hydrochloric 
acid, as this involves the risk of spoiling the culture experi- 
ments. In Europe, where as a rule all kinds of drying 
ovens, autoclaves, &c., are available, other methods may 
indeed be used, but even here alcohol is to be recommended 
to the mycologist in most cases. It is obvious that by this 
method all such articles as corks, filter papers, &c., which 
cannot be exposed to high temperatures, may easily be freed 
from germs. The remarkable efficacy of alcohol has long 
been known. Some authors indeed consider even a 14 per 
cent, solution as sufficient ; in the tropics this is, however, 
often not strong enough to kill the bacteria. The bacterium 
above mentioned as occurring in palm sugar showed itself 
particularly resistant, and only lost its germinative capacity 
when the solution reached a strength of 20 per cent. In 
general, 1 have used 75 per cent, alcohol, in which the germs 
are at once destroyed. 
When we have thus freed the nutritive solution from all 
germs, and so fulfilled the first condition for the establish- 
ment of a pure culture, every possible care must be taken to 
preserve it from any subsequent contamination from with- 
out. For this purpose I recommend a specially constructed 
flask, which is illustrated in the figures. It is an ordinary 
washbottle, whose blow-tube (a) is blown out into a 
