Bailey,— Puccinia malvacearum and the My coplasm Theory, 183 
to the ungerminated spores. It may even be suggested that the spores do 
not germinate because they have formed within themselves some substance 
which is toxic to themselves, and that this same substance, on escaping, 
reacts even more noticeably on the cells of the plant underneath. 
9. Histological distinction between growing seedlings derived from clean 
and ‘ infected * seed. The appearances described by Eriksson are similar to 
those which he had previously described in the case of wheat, and are open 
to the same criticisms which Marshall Ward 1 raised at that time. 
The present author has not had the opportunity of repeating this 
histological work, but has attempted to prove the presence or otherwise of 
the fungus in the* tissues by growing plants from seed onwards under con- 
ditions which afforded protection from outside infection. 
The manner in which these experiments were carried out and their 
results are shown in the next section of this paper. 
Experiments in growing Hollyhock Plants from Seed 
under Conditions excluding outside Infection. 
Dandeno, in the paper which has already been referred to, makes 
a record to the effect that he collected and planted many affected seeds, 
which were ‘ kept under conditions unfavourable to inoculation from external 
sources *, and that in no case did rust appear on these plants. He makes 
no reference to the manner in which the experiment was conducted nor any 
reference to controls. 
During the years 1912 to 1915 an attempt was made by the present 
writer to carry out a series of cultures under critical conditions. Two 
experiments were carried out during that time and will be described 
separately below. 
Experiment 1. 
The essential part of the apparatus used in this experiment was a large 
glass globe 2 about 20 inches in diameter, provided with two open necks at 
opposite ends of one diameter. 
The upper neck was about two and a half inches wide and the lower 
about three-quarters of an inch wide. 
The upper neck was plugged up with cotton wadding through which 
passed a glass tube which reached almost to the bottom of the globe inside. 
The end of the glass tube outside the globe was bent over at a right angle 
and passed through a rubber cork, which in turn fitted tightly into a wide 
glass tube filled with cotton-wool. By attaching an aspirator to this last 
tube, air could be sucked out of the globe from time to time, and fresh 
1 Marshall Ward : Recent Researches on the Parasitism of Fungi. Ann. Bot., 1905. 
2 The globe was of the same type as that shown in Fig. 2. 
