Brown . —Studies in the Physiology of Parasitism . I. 329 
along the cut surface results in the rolling apart of the upper and lower 
halves, so that the extract rapidly gains access to all parts of the disc; in 
rose petal discs the same effect is produced by the rolling back of the lower 
cuticle. 
When the active extract is injected into the tissue, the action may be 
very rapid. The most marked effects are seen in the case of floral structures, 
in which injection of the extract produces rotting and death within half an 
hour. 1 This has been found to be true of upwards of thirty species 
investigated, whence it would appear that the extract is destructive to floral 
structures in general. In the case of foliage leaves, the rate of action is as 
a rule much slower, but is nevertheless strongly marked in many cases— 
leaves of succulents, of Vicia Fab a , Viola, Petunia , Lactuca i Begonia , &c. 
In the case of leaves of a hard woody nature it has not been shown in any 
case that the extract has any action. Thus leaves of Aucuba , pitchers of 
Nepenthes , have afforded negative results. 
When tissues of lower plants were investigated in this respect, unexpected 
results were obtained. Nordhausen ( 1 . c.) records certain experiments in 
which moss leaves showed themselves very sensitive to the action of Botrytis , 
and it was in view of this statement, as also on account of their softness, that 
tissues of Bryophytes were expected to succumb rapidly to the action of the 
extract. Quite the opposite result was obtained, and in fact it is not too 
much to say that these forms show complete resistance to the action of the 
fungal extract. The following have been investigated : 
Thallus of Pellia , Fegatella ; leaves of Plagiochila , Funaria, and 
Mnium . 
In no case whatever was any definite alteration demonstrated, even 
after several days’ action of the extract, the latter being renewed from time 
to time. 2 
In view of this startling discrepancy, experiments were set up to see if 
any confirmation could be obtained of Nordhausen’s statements as to the 
action of the fungus itself. For this purpose small clumps of the above- 
mentioned plants were sprayed with a turnip extract suspension of Botrytis 
spores, which were then allowed to germinate. In the course of a few days 
the clumps were quite infested with the fungus, becoming in fact totally 
covered and hidden by the mass of mycelium. Even after this drastic 
treatment, the plants, both mosses and hepatics, were found to be only very 
slightly affected, appearing slightly limp and unhealthy, but showing no 
1 In the case of the soft petals of Gloxinia , Achimenes, Tradescantia, Saintfiaulia, &c., the 
effect of the extract is apparent within five minutes of the time of injection. . Further action of the 
extract leads to almost complete solution of these petals. 
2 In the case of the moss leaves examined, groups of cells here and there were seen to be dis¬ 
coloured, but in no case was anything like a general action of the extract shown. Similar and, as 
far as could be judged, equal discolorations were seen in the control moss leaves which had been 
kept in water. 
Z 
