14 TRANSACTIONS. 
2nd of December. 
Major BowbDEN, Vice-President in the chair. Twenty-six 
members present. 
New Member.—Mr John A. Moodie, Solicitor. 
Donations.—Mr Robert Thomson, Joiner, presented, through 
Mr James Barbour, the dove carved in wood and gilt which 
formerly stood over the canopy of the New Church, Dumfries 
(Greyfriars’). When that church was taken down the dove was 
purchased by the late Rev. Dr M‘Farlane and placed by him over 
his pulpit in Troqueer Church, which has lately been rebuilt. 
This interesting relic came into the possession of the contractor, 
Mr Thomson. Mr James M‘Andrew presented /uzcus tenuis and 
Rhyncospora fusca found by him in the district and now first 
recorded. Fifteen new rules were adopted, on the motion of Mr 
J. Wilson, the Secretary. 
COMMUNICATIONS. 
I. Certain Common Parasitic Fungi. By Mr Greorce F. Scorrt- 
Exuiot, M.A., F.L.S. 
The fungus (Peronospora infestans ) that causes the well-known 
potato disease consists of a delicate series of branching filaments 
that penetrate between the cells of the potato leaf and suck from 
them the materials that should feed it. By this procedure the 
potato leaf decays, and this causes the unpleasant odour that is 
one of the signs of the disease. The fungus is enabled to spread 
from one potato plant to anothe: by means of conidiospores. 
These are formed on the under surface of the leaf (giving rise 
to a sort of whitish bloom) on the extremities of a branched 
filament which is protruded through a stoma. The conidiospores 
are blown by the wind on to the upper surface of a potato leaf, or 
in some cases on an exposed tuber. If the weather happens to be 
wet, the conidiospores break up into 7 or 8 little “ swarm spores,” 
and these penetrate (in the case of the leaf) through the cuticle, 
and by germination produce a new series of filaments in it. 
(In the case of the tuber, the fungus makes its entrance by the 
“ eye.”) Towards the end of the autumn the fungus makes its 
way down the stalk to the tubers, and passes the winter in a latent 
condition in them. When the tuber germinates in spring the 
fungus grows, keeping pace with the growth of the young plant, 
which is thus doomed from its earliest days. A special kind of 
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