A NOTE ON JNDIAN WHEAT-RUSTS 
II7 
in detail. First; in P, ruhigo~vera the forms teleutospores 
on wheat ; in this Shibpur Rust^^ no teleutospores are formed on 
the wheat. It is true that a negative proposition is difficult to prove, 
and it may be objected that perhaps there were some teleutospores 
on the wheat which were overlooked. 
This may, no doubt, be the case ; we do not, however, think it 
probable ; it must be recollected too that, wherever this particular 
" rust’’ was found, the same absence of teleutospores was experienced ; 
and it should be remembered besides that, so far as the wheat itself 
was concerned, teleutospores were the main object of our search. 
Again, this “ Shibpur Rust ” apparently has a different host. The 
aecidial fructifications in the case of P, rubigo-vera are carried by 
a ** Borage ” ; in the case of the present species they appear io be 
borne upon a ** Composite.’^ The experimental infection of healthy 
wheat by the Puccinia on this Composite ” may indeed at first appear 
to be definite proof that this contention is sound. It must not, how- 
ever, be overlooked that one very serious source of possible error 
exists. The composite from which the infective spores were obtained 
grew in a neighbourhood where there was undoubtedlyrusted wheat. 
The conditions for the dispersal of spores were in this neighbourhood 
almost ideally perfect ; it is therefore always possible that the spores 
which were obtained from the Launea^ and which actually did infect 
the wheat, were not spores of the Pucctnia that lives upon the 
Launea^ but were spores from diseased wheat that had been accident- 
ally carried to the leaves of the Launea and were lying there 
among the spores proper to itself. 
To counteract this source of error specimens of Launea^ bearing 
spores, were sent to Calcutta from various places in Upper India. If 
the same possibility of error prevailed at JMozufferpur, it certainly 
did not exist at Neemuch or at Jeypore. But the heat and dryness 
of the season unfortunately prevented any of these check-infections 
from being carried out ; all the spores had in each case lost their 
vitality during the short time required for their transmission to 
Calcutta, It is to be hoped that, in another season, we or other 
workers may prove more successful. 
If the suggested; and certainly possible, connection between the 
Shibpur Rust ” and the Puccinia on Launea asplenifolia be ulti- 
mately made out, the necessity for distinguishing this ** Shibpur Rust ” 
from P, rubigo^vera will have passed beyond the region of debate. 
For in the first place Launea in this case bears uredospores, teleu- 
tospores and aecidia at the same time, whereas the ** Borages that act 
as ho^ts for Puccinia rubiga~vera carry aecidial fructifications only. 
