604 
Journal of Agricultural Research 
Vol. XXXI, No. 7 
used as inocula, while from young cultures the mycelium usually 
is transferred. The writer had never noticed any difference between 
cultures raised from sclerotia and those grown from mycelial transfers, 
but in order to get definite data on this point and to note in particular 
whether there was any tendency to change the manner or amount of 
microconidial production, or a tendency for other conidial forms to 
develop, the following experiment was conducted. Six cultures were 
selected, five of S. libertmna and one of S. intermedia From 
these cultures, two sets of transfers were made. In the first set only 
mycelium and the associated microconidia were used as inocula, 
while in the second set care was taken to transfer only sclerotia. 
These two sets of cultures were grown at room temperature in diffused 
light, and were transferred, in the manner just described, every 
month for nine successive months. Notes were taken on each 
successive generation at the end of one month’s growth, in an effort 
to discover any differences in growth and development between the 
cultures from the sclerotial and those from the mycelial transfers. 
At the close of the period there was nothing to indicate that it would 
be worth while to continue the study. The results of this experiment 
can be summarized by saying that the chief difference noted was in 
the rate of growth. The mycelial transfers grew much faster im¬ 
mediately on being placed on new agar, consequently producing 
more vegetative growth and forming sclerotia sooner than the 
cultures arising from the sclerotial transfers. The slower-growing 
sclerotial plantings, however, were comparable to the other transfers 
by the end of the month. There was no tendency to change from 
the normal way of growing in either series, and no more sclerotia or 
microconidia were produced than usual. 
EFFECT OF TEMPERATURE AND CULTURE MEDIA ON SCLEROTIA 
Cultures of Sclerotinia grown at room temperature maintain 
approximately the same relative size of sclerotia for a given species, 
provided a suitable medium is used. In cultural studies, however, 
the writer has often noted that the relative size of the sclerotia of 
different species does not remain the same when extremes of tem¬ 
perature are involved. In general, when the temperature is. near 
the minimum growing point for the fungus, the sclerotia have a 
tendency to be larger than the normal for room temperature. This 
is particularly so in the small sclerotial forms. S. intermedia on 
potato dextrose agar at 5 to 7° C. has been observed to form sclerotia 
2 to 4 mm. in diameter, while the normal for this species is 2 mm. at 
20°. On the other hand, sclerotia grown near the maximum for the 
fungus have a tendency to be smaller than normal for room tem¬ 
perature. Sclerotia of S. libertiana , which usually average about 
4 ixim. in diameter at 20°, have ranged from 1.5 to 4 mm., with an 
average diameter of 2.5 mm. when grown on the same medium at 30°. 
S. intermedia grows very poorly at this temperature and the sclerotia 
formed vary from 1 to 2 mm. in diameter. 
Changes in the size of the sclerotia have also been noted in cultural 
studies when apparently other factors than temperature were in¬ 
volved. A Sclerotinia was isolated from parsnip which produced a 
scant mycelium with numerous very small sclerotia. The first 
isolation plate and the first transfer to tubes of potato-dextrose agar 
