58 
Journal of Agricultural Research 
Vol. XXVI, No. X 
GERMINATION STUDIES 
Plate 12, Z, A', B', shows the method of germination of Monochaetia 
rosenwaldia. Note that the contents of the spore swell up to such an 
extent as to rupture the cell wall. This is followed by the extrusion 
of a very robust, frequently rotund, sometimes double “germ tube.” 
Germination took place in most cases after 24 hours, and was followed by 
vigorous growth. No conidia formed in the hanging drop cultures; 
instead, a peculiar chlamydospore formation was noted at about the time 
when the mycelium ceased to grow—that is, some three to four weeks 
after germination had started (PI. 12, C'). 
Since no conidia formed in the hanging-drop cultures, it was necessary 
to study the method of spore formation from material obtained from 
acervuli in other cultures. This method would seem to be as follows: 
Tips of some hyphae become rounded and swollen. These globular 
inflations soon become elongate, and are in the meanwhile separated 
from the sporophore by a septum. Gradually the other three septa form 
across the spore, while the two central cells pass through the grades of 
color already mentioned. The appendage at the apex seems to form 
last of all, by the attenuation of the apical cell or the prolongation of its 
walls. Plate 12 shows some mature spores on their sporophores in X, 
while Z illustrates some of the earlier stages in the formation of the 
conidia. 
In view of the fact that some investigators make the length of the 
sporophores a basis for specific distinction, measurements were taken 
of a number of these for comparison. Material grown in artificial media 
had to be used in this connection, for the sporophores in the acervuli on 
the inoculated branches, which supplied most of the material for the 
study of the morphology of the fungus, had shed their spores, and could, 
therefore, no more be distinguished from ordinary hyphae. Measure¬ 
ments of the sporophores are as follows: 
Material grown on an infusion of Moorpark apricot leaves: Extremes 
for length for 30 sporophores were 7 to 62.5 ju; 23.5 /* was the most com¬ 
mon measurement for length. Material grown on an infusion of Irish 
potatoes: Extremes of length for 20 sporophores were 8 to 26 n\ 13.5, 
19.5, and 26 11 were equally common measurements. 
The sporophores varied greatly in width in the same medium. They 
were often narrowest about midway and frequently tapering toward 
the base of the conidium; 1.5 to 4 seemed to be the range for the 
medium widths of most of the sporophores. 
These measurements indicate clearly the great variability of the 
sporophores in different media as well as in the same medium, a fact 
which is by no means surprising if it is remembered that the sporophore 
is after all a purely vegetative portion of fungus mycelium. The value 
of such measurements for the purpose of specific distinction seems there¬ 
fore doubtful. 
SUMMARY 
(1) The apricot gall disease, which is more striking than injurious, is 
readily distinguished from “ aerial crowngall, ” with which it is sometimes 
confused, through the fact that the galls are bark out-growths in which 
the wood tissue is not mingled; whereas in crowngall the wood is involved 
in the formation of the tumor. Unlike the tumors in crowngall, the 
galls in this disease are thoroughly permeated with gum. 
