1902] BRIEFER ARTICLES 63 
the host on which the second half grows. For instance, if I have teleu- 
tospores, found upon a grass in germinating condition, shall I sow 
them upon a geranium, gooseberry, buckeye, thistle, or some other one 
of a hundred or more plants known to bear aecidia ? I might try each 
one in succession, and hope eventually to hit upon the right one. But 
the chances of success by this method are few, in fact, according to my 
experience, far too few to warrant its use. On the contrary, in order to 
cherish any reasonable hopes of success it is necessary to possess very 
definite clues. The method of obtaining these clues I desire espe- 
cially to call attention to, for it seems to me that observation of this kind 
will add at times much interest to collecting, and provide valuable data 
to supplement that usually taken. 
To make the problem more concrete, I may state that during the 
present season I have grown from teleutosporic material the common 
aecidia on Sambucus, Erigeron, and Aster, and an aecidium on Ribes aie - 
that appears to be different from the common form. The teleuto- 
spores for these four species of rusts came from as many different spe- 
cies of Carex, and have heretofore been erroneously listed as Puccinia 
Caricis. The taxonomic significance of these results will be brought 
out when the data are ready for publication ; it is now only intended 
i — how I came to sow these particular teleutospores poe the 
. the is place, all observations affording clues( withsuchexcep- 
tions as the similarity in form between uredospores and aecidiospores 
to be detected only with the microscope, which are so rare as to Se 
_ Regligible) must be made in the field. For the most part they must 
_ be made previous to the season when the cultures are undertaken. It 
= is advantageous, indeed , to watch the same rusted plants, or clumps 
= areas of rusted plants, from season to season. In this way theinter- — 
_ @stis not so much centered in the specimens carried away, as in the 
& fungus crop that is left behind. When specimens are gathered, they — 
: ‘labeled not only with the usual data, but with suffici ently exact 2 
ions so that the spot may be found again. The same host plants — 
. pomined from site. to time as the ; succession of spore-forms 
me 
se, 
ote as It is like atching suct 
i the pleasure of collecting is ‘much agen, 
