10 
Journal of Mycology 
[Vol. 12 
therefrom uredospores were obtained also later teleutospores. 
The pustules were cursorily examined before used and nothing 
was observed but teleutospores. 
dr. Arthur's discovery of the aecidium. 
Before my work was published Dr. Arthur had the rare 
good fortune to demonstrate the aecidium stage of the Maize 
Rust. Twice I had, as I supposed, obtained uredospores by using 
teleutospores direct on Maize plants — and scant material yet 
remaining enabled me to get a third inoculation with spores from 
my teleutosporic pustules. As far as seemed consistent with prob¬ 
able success in this third attempt at inoculation the pustules were 
disintegrated and the mass of spores (with loss of course) was 
subjected to microscopic scrutiny; but no uredospores were seen. 
Doubtless further search should have been made — uredospores 
might have been found, and that, of course, would have been of 
far greater value than the successful inoculation. Dr. Arthur 
used aecidiospores of Oxalis to inoculate Maize. The final link 
in the absolutely complete demonstration was this only — to use 
teleutospores of Maize rust to secure the aecidium on Oxalis. 
This I did. 
WORK WITH THE TELEUTOSPORES IN I905. 
The chain of evidence was in fact complete — or at least 
neither Dr. Arthur nor myself longer could doubt that the life 
cycle of this Rust included three stages — aecidium, uredo and 
teleuto. Confidently therefore on my return from Guatemala I 
instituted experiments in the month of April and early in May, 
using teleutospores from sweet corn that had been exposed all 
winter. In due time the several Oxalis plants on which sowings 
were made responded generously and repetitions were equally 
satisfactory. 
REPETITION OF FORMER WORK. 
The theory I proposed one year ago, namely, that an aecidium 
might be suppressed at will (or under circumstances), I now 
abandon. It is very probable that a few uredospores viable were 
harbored by the teleutosporic pustules and these in that case of 
course gave the inoculation of the Maize. Uredosporic inocu¬ 
lation as shown by numerous experiments later was not difficult, 
but a very certain result to be anticipated whenever spores fell, 
or were placed, on the proper host. 
SIGNIFICANCE OF THE PHENOMENA OF UREDOSPORIC INOCULATION. 
The surprise that the rather rare aecidium of Oxalis should 
belong to the very common and very abundant Rust of Maize 
was shared by many mycologists. But the reinterpretation of 
my work — which does not seem irrational — clears up the mat- 
