194 Bailey. — Puccini a malvacearum and the My coplasm Theory. 
Table II ( continued ) 
Ref. No. 
No. of leaf . 
Dimensions 
{in inches'). 
Extent of disease. 
Remarks. 
Length of Length of 
lamina. petiole. 
G.G. 3 
12 
13 
14 
Expanding 
crown 
leaves. 
4 i 6 
4 4 
About 9 pustules of varying 
age. . 
About 9 pustules of varying 
age. 
No rust. 
>> 
Additional evidence of these being cases of outside infection is afforded 
in the further behaviour of ‘G.G. 3 \ The globe was replaced over the 
stump of this plant, from which all the leaves had been removed for 
examination. In due course new leaves developed from this stump, and 
these remained free from rust until six months later, when the globes were 
finally removed. 1 
It has been mentioned above that one of the plants in globes — 
No. G.G. 8 in the series — was inoculated with a suspension of oidial spores 
during September and October, but without result. Later on, further 
attempts at artificial inoculation were made on some of the other plants, but 
in all cases the result appeared to be negative. 
A summary of the history of all the plants in globes from October 26 
onwards is given in the following table. It will be observed that all the 
plants which had been infected finally developed rust, but only after an 
interval that made it appear improbable that the outbreaks were directly 
attributable to the inoculation. 
The fact that so many plants — six out of ten — did develop disease 
before the end of the experiment may seem remarkable, but, as has been 
stated above, the apparatus was no longer reliable, and it should also be 
borne in mind that a continuous current of air was being sucked into the 
globes through whatever channel offered the least resistance, and that the 
control plants on the bench alongside bore rust pustules throughout this 
period. 
With the exception of G.G. 2 and G.G. 3, all the globes had been last 
examined about a fortnight before the date on which they first showed rust 
in each case and had been described as ‘ free \ 
1 In this connexion it is interesting to note that Massee, in ‘ The Diseases of Cultivated Plants 
states that plants which have once recovered from the disease are immune from further attacks. 
As the result of two series of experiments on this point I have satisfied myself that no such 
acquired immunity exists. 
