on the Sporidia of Puccinia malvacearum (Mont.). 337 
the partition parallel to the window. Fig. 5 shows the result ; the 
germ tubes on the light side (a) of the partition (p) are all growing towards 
the latter, i. e. away from the light. On the other side (b), however, the 
spores lying in the zone of shadow have their germ tubes directed towards 
the partition, i. e. further into the shade. A little further away they are 
growing in all directions, whilst entirely beyond the influence of the shadow 
they are pointing away from the light of the window, A control cul- 
ture with a similar partition in the dark showed, as before, the germ 
tubes growing indifferently in all 
directions. 
Miyoshi 1 found in his work 
on the chemotropism of Fungi 
that light exercised no influence 
upon the germinating spores of 
the Fungi he used in his experi- 
ments. It should be noted, how- 
ever, that he only experimented 
with one obligate parasite, viz. 
the uredospores of Uredo linearis . 
For purposes of comparison 
similar series of experiments to 
those described were set up in 
which aecidiospores of Puccinia 
poarum , the conidia of Botrytis 
(sp.), Alter naria, Penicillium 
glaucum , and Peronospora para- 
sitica were employed. The results of these experiments testing the effect 
of light, as well as those already described for the sporidia of P. malvacearum , 
are summarized in Table II. 
Effect of unilateral light. 
All germ tubes directed away from light. 
Indifferent to light. 
All germ tubes directed away from light. 
Indifferent to light. 
>> >> 
) 1 
Fulton 2 in investigations on the chemotropism of Fungi obtained results 
which he regarded as negativing Miyoshi’s conclusions. He did not specially 
test the effect of light, but states that it probably does not enter as a tropic 
factor. This appears to be so for some cases. My experiments for Botrytis , 
1 Loc. cit. 2 Loc. cit. p. 105. 
No. of tests 
separately made. 
Spore. 
Sporidia of P. malva- 
cearum ..... 25 
Aecidiospores of P. 
poarum 6 
Botrytis (sp.) ... 12 
Alt ern aria (sp.) . . 4 
Penicillium glaucum . 6 
Peronospora parasiticum 6 
Table II. 
Medium of 
hanging drop. 
2 % gelatine 
2 % gelatine 
2 % gelatine 
2 % gelatine 
2 % gelatine 
Water 
N PjJj t 
/ 
1 J \ 
VS7'} 
j 
ill / 1 s 
u d 1 1 ^ t A 
( j < 1 A 
' 1J AWu 
' j * 
Fig. 5. A sowing of sporidia on both sides of 
a partition ( p ) of tin-foil ; the arrow indicates the 
direction of the light, and s is the shadow between 
the dotted line and the partition, x 45. 
