7 i 8 
Journal of Agricultural Research 
Vol. V, No. 16 
instances, they were unable to determine the conditions under which 
fruiting bodies developed, but they surmised that probably the lack of 
food supply was the causal relation. 
Other related genera have been studied more or less, and detailed 
accounts of the growth and fruit-body formation of several species of 
Phomopsis on the ordinary laboratory media have been given. (Roberts, 
1913; Harter and Field, 1913; Harter, 1914.) 
Plenodomus destruens has recently been described by Harter (1913), 
who has cultured the organism upon the ordinary laboratory media, and 
has determined its optimum temperature. For the most part the above- 
mentioned articles, written from a phytopathological point of view, have 
used the pure culture as a device for furnishing material for pathogenic 
studies, and the description of the organism in culture is largely for 
diagnostic purposes. 
METHODS OF INVESTIGATION 
As Plenodomus fuscomaculans had shown no form of reproduction 
under the ordinary methods of culture (see p. 724), it seemed to afford an 
excellent opportunity to try the effect of various environmental factors 
as a test of the applicability of the methods of Klebs to phytopathological 
studies. 
The strain of the organism used was the progeny of a single pycnid- 
iospore, isolated by the dilution method. This strain had been tested 
and was known to be pathogenic to apple. In 1913 another isolation 
was made from a second collection of material, and a second strain 
obtained and similarly tested. In all later work both strains were used 
in all experiments. Aside from slight differences in vigor of growth, the 
cultures gave the same reactions. 
All experiments were made in duplicate with each strain; hence, the 
experiments reported give results which are a summary from the record 
of at least two, and, in most cases, of four parallel cultures. 
The glassware used, unless otherwise indicated, was the ordinary 
German glass. All glass culture dishes, when other than tap water was 
to be used, were cleaned by immersion overnight in cleaning fluid, fol¬ 
lowed by four rinsings of tap water and one rinsing of distilled water. 
When water of a higher purity than ordinary distilled water was to be 
used in the medium, the vessels were given an additional rinsing with the 
4 purer water. 
The most commonly used culture dishes were small glass preparation 
dishes, or capsules, of about 35 c. c. capacity. These had a loosely 
fitting cover which rested upon a shoulder of the bottom. 
The chemicals used were those of Kahlbaum. Solutions of various 
chemicals were made up as weight-normal solutions (1 molecular weight 
in grams in 1 liter of water); and where chemicals contained water of 
crystallization, this was added in computing the molecular weight. 
