on the Sporidia of Puccinia malvaceartim (Mont.). 333 
was placed a drop of water (b) to ensure a saturated atmosphere. A large 
rectangular cover-slip was used, and the whole slide with the cell was 
inverted so that the sporidia, when produced, would fall on the cover-glass (c). 
A good sowing of sporidia was usually obtained in twelve hours. The 
sporidia were found to germinate equally well when sown in a thin film of 
water, or on the surface of % per cent, gelatine. For most of the experi- 
ments the sporidia were allowed to fall on a drop of 2 per cent, gelatine 
spread on the cover-glass of the cell. In this way the possibility of the 
direction of the germ tubes being altered by the necessary movement of 
the cell was avoided. 
The first series of experiments was arranged to test whether fragments 
of various leaves, placed near the germinating sporidia, exercised any 
influence on their germination or on the subsequent direction taken by 
the germ tubes. The leaf fragment in each case was cut with a clean 
scalpel, washed with distilled water, roughly dried on filter paper, and 
placed on the surface of a drop of 
gelatine on the cover of a cell. The 
o 
sporidia were sown around the leaf 
fragment by the device already de- 
scribed, and all the cultures were kept 
in the dark. These were examined 
after twenty-four hours and the results 
were as follow. For fragments of the 
leaves of Althaea rosea , Ranunculus 
Fie aria, Stellaria media , Oxalis (sp.), 
Fuchsia (sp.), Solanum tuberosum , 
Sinapis nigra, Crataegus. Oxyacantka, te ‘ f ' ^ 
Tropaeolum (sp.), Geranium Robertia- 
num , Mercurialis perennis , Trade scantia (sp.), Quercus Robur, and Citrus 
Aurantium , vigorous normal germination was obtained. For fragments 
of the leaves of Primula vidgaris and garden geranium (. Pelargonium ) 
germination was, to a large extent, inhibited. Although in these cases no 
normal germ tubes were produced, some cases of abnormal germination 
were observed in all the tests. Fragments of the leaf of Eucalyptus 
globulus showed similar inhibitory effects, although some normal germ 
tubes also appeared in this case. 
From these results it is clear that the germination of the sporidia in 
close proximity to most of the leaf fragments was quite normal and 
vigorous. No difference could be detected between the behaviour of the 
sporidia germinated near a fragment of the leaf of the normal host-plant, 
Althaea rosea , and that of sporidia near leaves of many of the other species 
used in these experiments. Whilst no positive stimulatory results were 
obtained, it has been mentioned that certain negative effects were seen with 
Fig. 2. Sporidia in a culture near to a 
