65 
tions to pure water. They frequently die or, at all events, experience 
a weakening in tlieir further development. In order to avoid these pos¬ 
sible injuries to the sprout conidia of the smut fungi, I transferred the 
germs while still sprouting vigorously, from the culture flasks to the 
atomizer with the precaution to place in this first a diluted aud steril¬ 
ized nutrient solution. I knew to a certainty by previous experiments 
that in this the sprouting germs would not be injured, but rather would 
continue to sprout for a short tijne so far as the nutrient substances 
made this possible. In this way, it is true, a new source of error, the 
loss of time, is introduced, namely, the time in which the germs, sprayed 
upon the host plants by the atomizer, continue to sprout in the sur¬ 
rounding droplet before they grow out into germ tubes. However, 
without this error the experiment sometimes fails, because we can not 
spray into the host plant or administer to it the fungous germs in such 
ways as is customary in experiments with animals, but must apply them 
externally. The mixing of the fungous germs with the diluted nutrient 
solution in the atomizer can be regulated at pleasure according to the 
quantity of the germs. The mixture was always exactly tested before 
each experiment and not used until the trials each time had shown that 
at least thirty germs were present in the tiniest mist-like droplets. 
The infection itself, to wit, the spraying with the fuugous germs, was 
performed in shallow tin boxes made for the purpose. In this the 
nascent seedlings of the host plant were placed entirely uncovered, on 
soil from the field, and after the spraying, could be kept by means of a 
glass plate cover in a uniformly and suitably damp atmosphere at about 
10° 0. This was to hinder the evaporation of the sprayed droplets 
and at the same time to favor the development of the sprout conidia 
into threads aud the penetration of these into the host plants. After 
10 to 12 days the infected plants were set out in the open field, so as to 
make possible their full development and at the same time to give an 
opportunity for the development of smut in their spikes. But even 
with these very careful methods there were still serious obstacles to 
the success of the infection. The young seedlings exude, through 
stomata, especially at the apex of the shoot, drops of water which in 
running easily wash away the fungous germs which have been sprayed 
on, and in consequence may hinder their penetration and thus affect 
the result of the experiment. This and the already intimated sources 
of error in infections, i. e ., in the transference of the germs directly 
to the seedlings, make it probable at first sight that the infection 
will not succeed equally well in all the plants used for experiment, 
but rather that it will be successful only in a portion of these. But 
this indefinite per cent, of accidents is still further much increased 
by the circumstance that in the different forms of grain-smut the recept¬ 
ive stage in the seedling is so very transitory that (as later results of 
experiments show conclusively) only those fungous germs which pene¬ 
trate into the just developed seedling above the root node, and in this 
