:XXX TEOCEEDINGS OF THE KOYAL HORTICULTUBAL SOCIETY. 
Mandarine Oranges striped. — Mr. Hudson brought some fruit which 
always had sHghtly raised ridges, on a line with the backs of the carpels, 
and green. They proved to be quite superficial, only retaining the 
chlorophyll grains, which had disappeared elsewhere. 
Acorn with three Enihryos. — Mr. Sewell, of Buckhurst Hill, Essex, 
•on growing an acorn in water found that it sent up three stems. They 
proved to arise from three distinct embryos within the common husk. 
"Such polyembryonic conditions occasionally, but not very frequently, 
occur. 
Douglas Fir diseased. — Dr. Smith reports that the portions of trees 
sent exhibit attack by the fungus Phoma pithy a, Saccardo. The twigs 
bear numerous black points, which, under the microscope, are seen to be 
receptacles containing the filaments from which the tiny one-celled 
colourless spores or conidia of this Phoma are given off. The fungus 
appears to infect the bark of young shoots unfolding from the bud ; tjie 
twig may grow for several years ; hence the diseased part, as is shown by 
specimens, may occur on twigs several years old. The fungus grows 
slowly under the bark which dies, and no new rings of wood are formed; 
the twig, however, continues to increase in thickness below and frequently 
^Iso above the diseased area, which thus shows as a constriction. After 
the fungus has ringed the twig, all green parts die off, and the needles 
fall, as in specimens. There has also been an abnormal formation of 
resin in the bark of diseased parts ; hence the resin boils, many of which 
have burst, leaving open wounds. The disease was first ascribed to this 
fungus by Rostrup about 1885 ; later descriptions of its occurrence on 
Douglas Fir in North Germany were given by Boehm (1896). I only 
know of one record for Britain, by Professor Sommerville {" Trans. 
R. Scottish Arboricultural Soc," vol. xv. 1894, p. 191). The fungus is 
nearly related to Phoma ahietina, described by Robert Hartig as a disease 
on Silver Fir. Other species of Phoma occur on Conifers. 
Nothing definite has been done in the way of remedy. Two courses 
■appear possible : — (1) Destruction of young trees attacked low down ; if 
the attacks be recognised early, diseased parts might be pruned without 
disfiguring the trees ; (2) spraying with a fungicide, but with which one 
requires to be ascertained by experiment. 
Potatos diseased loith Scab, &c. — Dr. Smith also reports on samples 
received from Mr. Escombe, Penshurst, in August, 1899. Prolonged 
•cultivation of the fungi showed several species, so that it was difficult to 
detect which was the primary cause of the disease. " The skin of the 
Potato bore two distinct forms of disease: (1) scab, the cause of which is 
not yet known ; (2) dark brown bodies adhering to the skin, called 
Bhizoctonia solajii, being a mycelium of some unknown fungus. Other 
fungi present appeared to be the Potato dry-rot {Fusarium solani) and 
the Potato mildew (Phytopthora infestans).''' Dr. Smith proposes to 
continue the culture, and to add a further report hereafter. Mr. Hudson 
observed that scab frequently appears on Potatos when pig manure has 
been added to the ground. Such would appear favourable to the fungus 
which causes it. 
