Feb. 1903] Uredineous Infection Experiments in 1902 
7 
days, a longer period than most experimenters consider neces¬ 
sary. 
It is thought by some who have carried on uredinous inocu¬ 
lations extensively, that infection work in advance of the normal 
season of the parasitic species is fruitless effort. This is per¬ 
haps true in many cases, but my experiments with Puccinia at- 
kinsoniana shows that it may be profitable. With this species 
inoculations were made on Sambucus canadensis April 7, the 
host-plant having been transplanted to the greenhouse January 
10. The old leaves of Carex lurida harboring the teleutospores, 
exposed in their natural habitat all winter, were placed in the 
warm greenhouse a month and a half in advance of their use. 
Evidences of successful inoculation were noticeable April 15. By 
this early success it was possible to„ verify the result by repetitions 
of the experiment, as was done April 19 with corroborative 
result, also again April 25 with similar outcome, and for the 
fourth time — on host-plants growing out of doors — May 15, 
with a quadruply conclusive result. Using the teleutospores of 
Puccinia bolleyana on Sambucus canadensis in the greenhouse 
April 24, spermogonia and secidia were obtained. This experi¬ 
ment was repeated May 24 on plants growing out of doors and 
in due time the former result was corroborated. 
By this pre-season inoculation when possible, the correctness 
of first results can be verified the same year. This is advanta¬ 
geous — especially in the remarkable case cited above where 
apparently similar tecidia have been obtained on Sambucus by 
sowing spores of — as heretofore understood — two morpholog¬ 
ically different species. 
The experiments enumerated below include failures as well 
as successes. The latter can be repeated for verification and the 
former may to some extent, perhaps, be a guide to other ex¬ 
perimenters. When work on the American species has been more 
extensively performed, the literature can doubtless be saved the 
burden of so numerous failure-records. It may yet be profita¬ 
ble, perhaps, to undertake more or less work with barely per¬ 
ceptible or vaguely suspected clues, though the advantage of ex¬ 
periment with previously observed evidence or very strong hints 
of relationship is fully appreciated. 
PUCCINIA ATKINSONIANA DIET. ( 3 ) FROM CAREX LURIDA. 
Exp. 1. April 7. Teleutospores sown on Sambucus canadensis. 
— Spermogonia appeared April 15; aecidia April 24. 
Exp. 2. April 19. Teleutospores sown on Sambucus canadensis. 
— Spermogonia April 25; aecidia April 30. 
Exp. 3. April 19. Teleutospores sown on Sambucus canadensis. 
_ — Spermogonia April 25; aecidia April 30. 
( 8 ) Puccinia sambuci (Schw.) Arthur n. n., Bot. Gaz. 35:15. Jan. 
1903. 
