202 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
Poplars, New Balsam. By A. Henry (Gard. Chron. April 29, 1916, p. 230 ; 
with 2 figs.). — These are Populus balsamifera var. Michauxii, and a hybrid of P. 
deltoidea, L., var. monilifera, A. Henry, and P. balsamifera, L., named P. Baileyana, 
but corrected on p. 274 (May 20) to P. Jackii, Sargent, an older name. — E. A. B. 
Potato Canker, A Contribution to the Life-history of Spongospora subterranea. 
By L. O. Kunkel {Jour. Agr. Res. iv. pp. 265-278; pi.). — The author is led 
by his observations to conclude that not single cells but a plasmodium invades 
the healthy tissue of the potato tuber, pushing down between the cells and 
finally infecting them. The invaded cells are stimulated to abnormal growth 
and division. Tubers affected by canker or corky scab and stored are apt to 
spread the disease to others, for the spores germinate and produce amoebae 
which form plasmodia which cause secondary infections. The plasmodia 
feed on the tissue around the old canker spot. The author has observed the 
germination of the spores and believes he has obtained plasmodia on culture 
media. — F. J. C. 
Potato, Late, and Blight Fungus, Persistence in the Soil. By F. C. 
Stewart (U.S.A. Exp. Stn., New York, Bull. 367, Oct. 1913). — Boxes of soil 
containing potato haulms and tubers attacked by Phytophthora infestans were left 
in the field until January 20, when they were brought into a house and planted 
with potatos. Some of the plants raised were sprinkled with an infusion of the 
soil containing decaying tubers and stems, the air in the chamber being kept 
saturated with water. No infection with Phytophthora resulted, and the author 
concludes that the presence of diseased tubers in the soil does not increase the 
risk of an outbreak of the disease. — F. J. C. 
Potato, Phytophthora infestans in. By I. E. Melhus (Jour. Agr. Res. v. pp. 71- 
102, Oct. 1 91 5 ; pi.). — The author's experiments lead him to conclude that the 
mycelium of the potato disease fungus, Phytophthora infestans, grows in potato 
tubers and finally reaches the sprouts. Its growth is retarded below 5°C. and 
in dry soil, but infected tubers rot rapidly in warm wet soil. A temperature 
of 23°-27°C. and a well-watered soil are most favourable to the spread of the 
fungus in the tuber and its growth into the sprouts. The mycelium grows from 
the tuber into the stem, where it travels up to the surface of the soil and then 
forms spores. The planting of diseased tubers may thus cause an outbreak of 
the disease. Such outbreaks may start from single infected shoots. — F. J. C. 
Potato Scab and Sulphur Disinfection. By C. D. Sherbakoff (U.S.A. Exp. Stn., 
Cornell, Bull. 350, Aug. 1914 ; figs.). — The scab referred to is that produced 
by Actinomyces chromogenus (Oospora scabies). The experiments show that 
heavy dressings (350-400 lb.) of sulphur incorporated with the soil reduce the 
amount of scab to a marked extent, but do not completely eliminate it. Such 
dressings are likely to reduce yield, while light dressings, e.g. 100 lb. to the acre, 
may have a fertilizing effect, but are far less effective checks upon scab. [It 
may be added that land which received a medium dressing of sulphur in 191 4 
produced scabby potatos at Wisley in 191 5 in varieties in which the seed tubers 
were scabby.] — F. J. C. 
Potatos, Bordeaux Mixture versus Lime-sulphur as a Spray for. By M. 
T. Munn (U.S.A. Exp. Stn., New York, Bull. 397, Feb. 1915). — This bulletin 
describes the continuation of experiments carried out in 1911-1912, Bulletins 
347-352. ' 
The results were exactly the same, and go to confirm previous results, 
that lime-sulphur should not be used as a potato spray. — C. P. C. 
Pot-bound Plants, Danger in Planting. By Alex. M. Wilson (Garden, 
Feb. 20, 1915, p. 87). — This danger is illustrated by two photographs of a plant, 
Pittosporum Colensoi, which was planted five years previously. The roots, 
following the curvature of the pot, had gradually strangled and constricted the 
stem to such an extent that it had only required an extra puff of wind to effect 
complete severance. — H. R. D. 
Primulas, Some New, from China (Jour. Soc. Nat. Hort. Fr. April 191 5, 
p. 50). — Mgr. Leveille, in Le Monde des Plantes, March 1915, has described six 
new species of Primula discovered by E. Maire in Yunnan, a district known to 
be particularly rich in varieties of this plant. 
These six are : C. vxrqims Leveille, growing at a height of from 3,300 to 3,400 
metres, bearing 2-4 bright-blue flowers ; P. pirolaefolia Lev. — flowers blue or 
