226 
Journal of Mycology 
[Vol. 9 
able in any case to use material untested or that has proven re¬ 
fractory under trial — and I do not speak wholly without expe¬ 
rience in regard to this matter. The artificial conditions that 
must in all cases obtain, can reasonably be supposed responsible 
for occasional negative results. In case the spores sown actually 
infect the host, nothing was gained by the labor and loss of time 
in the pre-germination tests. These suggestions make it desira¬ 
ble that I insist on the slight stress that should be placed on neg¬ 
ative results; they should never be taken as necessarily conclu¬ 
sive. When we reflect on the very many possible causes of fail¬ 
ure in connection with any artificial infection no valid objection, 
in my opinion, can be urged against the view presented. On the 
other hand a positive result under properly imposed conditions 
and crucial exactions settles the question at once — though repe¬ 
tition only would satisfy very skeptical minds. 
Relative to the experiments outlined below, I may say that 
twenty-two species of Rusts were used, and in case of nine of 
them inoculations were successful. This is about the same ratio 
between success and failure as obtained in the work of the pre¬ 
vious season. In a few cases the failure was a foregone conclu¬ 
sion, due to poor “seed” or unsatisfactory host plants; still in 
spite of the narrow or negative chances of success inoculations 
were attempted. An unusually large number of tests were made 
with the Sunflower rust. Nineteen species of Helianthus were 
used and Rust from four species applied — though unfortunately 
with very meager results, it must be confessed — and in some 
other cases an unusually large number of host plants were used; 
it therefore happened that the total number of inoculations, Nos. 
68-260, was relatively quite large, namely 193. Turning now to 
the details of the experiments, recording briefly the facts in each 
case and commenting as seems necessary the report is as follows: 
PUCCINIA ANGUSTATA Pk. from SCIRPUS ATROVI- 
RENS Muhl. 
With material collected at Sandusky, Ohio, in April 1903, 
repeating the culture of this species — the connection of which 
with Aecidium lycopi Ger. was originally determined by Dr. 
Arthur, a single experiment as given below was undertaken. 
The teleutospores sown on Lycopus americanus produced the 
aecidia in abundance, thus corroborating Dr. Arthur’s work, and 
obviating the necessity of further explanation here. The record 
of the experiment is as follows: 
Exp. 180. May 28. Teleutospores from Scirpus atrovirens Muhl. ap¬ 
plied to Lycopus americanus Muhl. June 6, spermogonia 
abundant; June 10 , aecidia abundant. 
