1905] BRIEFER ARTICLES 227 
than those that were making little or no apparent growth. A few slowly 
growing plants were repeatedly inoculated without success until the plants 
were given extra care and stimulated so that they began to grow more 
vigorously. Some carnations, grown in small pots, were each inoculated 
five or six times at intervals of about twenty days, without any of the 
inoculations being effective. These plants grew very slowly, were slender 
and produced only one, or at most two, sma!] blossoms. 
Certain varieties of carnations are known to be more susceptible to the 
rust than others; among these are Uncle John and Daybreak. Other 
varieties are practically immune. The green-leaved varieties are con- 
sidered by carnation growers to be more susceptible than the more glaucous- 
leaved ones. The writer has noticed that there was a difference in the 
period of incubation of the rust when both green- and glaucous-leaved 
species of Dianthus were inoculated at the same time. 
A lack of susceptibility to inoculation, similar to that noted for Aspar- 
agus and Dianthus, occurred when seedling onions were inoculated with 
the asparagus rust. The inoculations were begun as soon as the seedlings 
appeared above ground, and were repeated at intervals until the seedlings 
were two months old, when almost every inoculation was successful. 
From the resulis obtained, not only with the rusts referred to, but with 
other fungi, it would seem that plants, like animals, are not equally suscepti- 
ble to infection and inoculation at all times. The negative results obtained 
by other investigators, as well as by the writer, may be attributed in some 
Instances probably to a lack of susceptibility of the host at the time the 
inoculation was made and not to a failure of the spores to germinate or 
to the way the inoculation was made. At some other period the same 
Plant might have been susceptible. ‘The state of growth of a plant seems 
to have much to do with the success or failure following an inoculation, as 
Well as conditions of temperature and moisture-which favor the germination 
of the spores. : 
It was determined in some of the earlier inoculations that the season, 
temperature, and sunshine exerted a marked influence on the period of 
‘ncubation of the asparagus and carnation rusts. It was also thought that 
“aog =a some difference ; for when twenty to thirty plants were eee 
=e rg as in a box or large flowerpot, the period of nae a 5 
i ies - each of the plants inoculated at the same time varied 0 é 
urs In most instances, while those that were of the same age ani 
stown in different soils showed more variation. 
: haem for testin g whether a difference in soils would bring about 
€ in the period of incubation of a rust, a stock plant, a green- 
