1 913- Irish Societies. 97 
DUBLIN MICROSCOPICAL CLUB. 
March 12. — The Club met at Leinster House, J. H. Woodworth 
(President) in the chair. 
Dr. G. H. Pethybridge exhibited a new species of fungus {Phy- 
tophthora erythroseptica) which he had discovered to be the cause of a 
specific form of rot in the potato tuber which is quite distinct from that 
caused by P. injestans, or by any of the hitherto described pathogenic 
bacteria or fungi, and for which the name " Pink Rot " has been suggested. 
The interest of the fungus lies not alone in its being new to science, but 
more in the fact that its mode of sexual reproduction is quite different 
from that described for any fungus up to the present. The female organ 
(or oogonium) at its inception enters the male organ (or antheridium) 
at or near the base of the latter, grows up through it, bursts out at the 
summit, and forms there the oogonium proper, in which a typical thick- 
walled resting spore is developed. Whether actual fertilisation occurs 
or not has not yet been determined, but if it does it must take place before 
the formation of the oogonium proper, or of the oosphere within it. In 
conjunction with Mr. P. A. Murphy he had also found that the recently 
discovered resting spores of P. injestans as well as those of P. Phase oli 
are developed in the same way, as are also probably those of Coleman's 
P. omnivora var. Arecae. Those of P. Cactoriim, P. Syrnigae, etc., are, 
however, formed in the usual way by the penetration of the oogonium 
laterally by an extension from the antheridium. Hence the name 
Phytophthora is to be retained for those species only which agree with 
P. erythroseptica in their mode of sexual reproduction, while that of 
Nozemia is suggested for the other species formerly included under the 
genus Phytophthora. Full details will be found in the Scient. Proc. 
Royal Dublin Society, vol. xiii., nos. 35 and 36, 191 3. 
R. Southern showed a specimen of Amphioxiis lanceolatus (Pallas), 
dredged in 20 fathoms in Dingle Bay, on a bottom of fine gravel and 
sand. This species has previously been found in Bantry Bay, and is 
widely distributed on the shores of the North Athlantic, Mediterranean, 
and Ceylon. The distinctive characteristics of the species were demon- 
strated, and its position as a primitive vertebrate discussed. 
Sir F. W. Moore showed the labellum of Masdevallia triangularis, a 
little Orchid from Colombia. The lip in this species is sharply bent 
back on a very delicate and mobile joint, so that the apex stands in front 
of the column, and on the apex is borne a group of dark hairs, apparently 
black in colour, but when examined under the microscope they are seen 
to be dark brownish red. A slight pressure causes the Hp to bend at the 
hinges, and on being released it quickly springs back again. The peculiar 
structure of this hinged joint was clearly demonstrated. 
