Marshall Ward. — On a lily -disease. 
347 
with cotton-wool after five minutes 5 boiling, and while steam 
was rushing out. Next day the boiling was repeated for ten 
minutes ; and after yet another twenty-four hours the boiling 
was again repeated, and so on. This well-known process of 
discontinuous sterilising gives excellent results. 
In charging the flasks with spores I abandoned the method 
of sowing with the point of a heated needle, because it was 
not possible by this means to get any idea of the number of 
spores taken up, and still less of the purity of the sowing. 
The following modification of the ordinary process gave 
satisfactory results. 
Perfectly clean sowings were made in drops of the sterilised 
culture-fluid on small cover-slips which had been heated until 
nearly red-hot, as if for culture in hanging drops ; I need not give 
details as to the precautions taken, but of course the cover-slips 
were not touched after sterilisation except by heated forceps, 
needles, glass, etc. The sowings, as made, were examined under 
the microscope, the cover-slip resting on sterilised glass or metal 
rings, so that the drop hung from its lower surface. When I was 
satisfied by microscopic examination that the sowing was clean 
— i. e. contained only the Botrytis-conidia — the cover-slip was 
lifted by forceps at one corner, the cotton-wool plug removed 
for a moment from the neck of the flask, and the sowing and 
cover-slip dropped bodily into the culture-liquid in the flask ; 
then the plug was replaced and pushed well in, and the flask 
labelled and placed on a shelf, where it remained perfectly still 
at a suitable temperature. 
In the course of three days the tiny mycelia can be seen 
on the surface of the liquid in such flasks, and in less than a 
week it is usually possible to decide whether after all care a 
foreign spore has obtruded (as will happen occasionally) in the 
culture. In a fortnight the mycelia have coalesced, and 
cover the liquid as a grey sheet : further growth results in 
corrugation or folding of this sheet as it tries to extend in 
the confined space. 
None of the hyphae dip far into the liquid, nor do the 
aerial hyphae project far from the surface ; at the margins, 
A a 2 , 
