2 
PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
Moreover, the size of the whole plant is very different, 
as is its general appearance. Are these points, then, 
of sufficient importance to make flexile be regarded as 
a distinct species? Most authors have thought that 
they are not, but then they have considered other 
ferns (such as the Prickly Shield Ferns— Polystichum 
aculeatum, lobatum, and angulare, and the Woodsias— 
hyperborea and ilvensis), with distinctive characters not 
a bit more marked than those which separate alpestre 
and flexile, entitled to specific or sub-specific rank. 
Why, then, have they refused it to the two ferns under 
consideration ? It is probably on account of the 
limited distribution of flexile. Had it been found over 
a wider area of the earth’s surface than Scotland, it is 
possible that many authors would have considered it at 
least a sub-species of alpestre, if not a full species. 
(Specimens in illustration of this paper have been 
deposited in the Society’s Herbarium ; and the paper is 
published in full in the Scottish Naturalist for 1881). 
2. “On Club-Root," or “ Finger-and-toe" in Turnips. 
By Mr A. Stephen Wilson, Aberdeen ; commu¬ 
nicated by the Secretary. 
It was pointed out that it was in connection with 
the turnip crop that the disease pressed itself on 
popular as well as on scientific attention. In its 
mature condition, the fungus ( Plasmodiophora brassicce) 
which gave rise to club root, consisted of globular 
spores which had a yellowish tint when aggregated in 
the cells of the club. In diameter he found them to be 
•0044 mm., or nearly three times the size assigned by 
Woronin. Many of them were mature in August and 
September, but clubbing went on throughout the 
winter; and the spores, at whatever time ripe, were 
capable of resisting all meteoric influences, such as 
drought, rain, and frost, remaining bright and intact 
during their period of rest—if indeed it was rest, and 
not some occult progress—and ready for action, either 
when a certain time had elapsed or when a certain 
degree of solar influence had been applied. The spores 
then, on the application of moisture, rapidly gave rise 
to variously-shaped amoeboid forms, and when a few of 
these coalesced they aggregated into what seemed a 
mere plasm. Although he had seen these forms 
escaping from the spores after a wriggling struggle, they 
were always more or less blunt at all points, not present¬ 
ing, as far as he could detect, the whip-like cilium 
attributed to them by Woronin. He would not 
dogmatise, as the point had not been sufficiently 
observed, but he thought it was probable that it was in 
a condition of plasm that the root hairs or epidermal 
cells came in contact with this fungus, and absorbed it 
into the root. A period of rapid growth in the turnip 
after genial rains, such as characterised this season, was 
peculiarly favourable to the demands of the fungus. 
The moisture was sufficient to bring the spores dissemi¬ 
nated in the soil into a plasmodic condition, and the 
rootlets running out in all directions were sure to come 
across the ambush of some of the burglars—for 
experiment had shown that earth mixed up with the 
spores contained in rotten clubs reproduced clubs on 
the plants grown in it. Clubbing was thus artificial 
bulbing produced by a fungus of the very simplest type. 
The plants call up bulbing by natural laws; the para¬ 
sites call up bulbing by their enchantments. That the 
cause of clubbing is really a fungus or vegetable 
parasite under some class cannot be doubted by any one 
who will look at a few sections of turnip roots; for in 
these the development i3 much more easily observed 
than in the woodier roots of the cabbage. As the loss 
arising from “finger-and-toe” amounted to many 
thousands of pounds yearly, was it too much to expect 
that before long the agriculturists of Great Britain will 
appoint one or more cryptogamic botanists solely 
devoted to the fungi of the farm ? The one question 
which the agriculturist had to ask of the cryptogamist 
was—not what is the nature and what are the properties 
of a destructive fungus; no, he did not want knowlege, 
he wanted money, and he asks—Can you give us a 
cure ? He would ask agriculturists, had they done any¬ 
thing to deserve a cure ? Let them take such measures 
in this matter as the large interests of agriculture 
demanded ; and if cures were not forthcoming, the 
knowledge would be gained that agriculture must adopt 
methods under which cures were unnecessary. 
(Specimens of club-root, and also microscopic slides 
of the fungus, were exhibited in illustration of the paper, 
and presented by the author to the Museum). 
Mr Parker, M.P., in proposing a vote of thanks to 
the writers of the papers, said he was sorry that he was 
not able to contribute anything to the discussion on 
either of the subjects. Both of them were beyond his 
attainments in science altogether, and he thought that 
