12 NORTH AMERICAN SORDARIACEAE 
sure being placed on the cover to rupture the perithecia, the 
superfluous liquid being wiped off; the cover was then sealed im- 
mediately with marine glue. In the other case the objects were 
mounted in water and arranged as desired when a drop of dilute 
glycerine was placed at the edge of the cover. Such mounts were 
allowed to stand for two or three days before sealing. The gly- 
cerine mounts are less liable to loss owing to imperfect sealing 
than the others ; but they have the disadvantage of showing less 
detail, which is highly objectionable with such delicate structures. 
Rough cultures such as those described above, although fur- 
nishing the ordinary facts required for taxonomic purposes were 
not of sufficient purity and ease of manipulation for some features 
of the investigation. It was, therefore, necessary to resort to other 
means of culture, suggestions for which were obtained mainly from 
the works of Zopf and Pfeffer. 
As stated in a previous paper,* the first approximately pure 
cultures were made on a substratum of filter paper soaked in vari- 
ous decoctions. Sometimes decoctions of ash leaves or horse 
manure was used, at other times prune or apple juice. In many 
ways the most satisfactory culture substratum was prepared by 
soaking thin slices of the trauma of Polyporus betulinus with some 
of the decoctions given above. This was found especially good 
for the development of Sordaria fimicola and Pleurage curvula. 
In preparing this culture the dry sterilizing oven was never allowed 
to reach a temperature of over 135° C., because of the danger of 
charring the mycelium. This temperature when continued for 45 
minutes was found sufficient for sterilizing purposes. The decoc- 
tion was sterilized by the ordinary fractional method. In making 
my first cultures great difficulty was experienced in keeping out 
spores of Mucor. From the nature of the substratum on which 
the fungi grow naturally, it was impossible to keep out bacteria ; 
but on paper and Polyporus cultures these did not interfere very 
much, the moulds being by far the most troublesome. The most 
successful method of securing the spores of the fungi free from 
mould spores consisted in washing a single perithecium on a glass 
slide in several changes of distilled water, the water being applied 
drop by drop and absorbed with blotting paper as it ran down the 
* Bull. Torr. Club, 26: 432-444. 1899. 
