Pflanzenkrankheiten. 
281 
t-il tous les Ch£nes ä feuilles caduques? (La Feuille des 
jeunes Naturalistes. 1 er nov. 1908. XXXIX. p. 26—27.) 
Les Chenes americains cultives en France ont paru indemnes 
ä Guinier et ä Lapeyrere. Seul le Quercus rubra a offert au premier 
de ces observateurs quelques taches limitdes ä la face inferieure des 
secondes pousses (pousses d’aoüt). Les recherches experimentales 
lui ont demontre que le mycelium se developpe sur les jeunes feuil¬ 
les, mais disparait promptement. Le Quercus palustris s’est montre 
absolument refractaire. 
D’apres Coulfon, les cultivateurs de la Mayenne ont garde le 
Souvenir de deux invasions anterieures du blanc de Chene, dont la 
derniere remonte ä 1903. P. Vuillemin. 
Hariot, P., Sur l’Oidium du Chene. (C. R. Ac. Sc. Paris CXLVII. 
p. 816—818. 2 nov. 1908.) 
Le parasite qui cause la maladie nouvelle du Chene est VOidium 
quercinum Thümen. Son importation d’Amerique est improbable, 
parce qu’il respecte ä peu pres totalemant les Chenes americains 
importes en France. II n’a rien de common avec YErysiphe Quer¬ 
cus M£rat qui appartient au genre Phyllactinia. P. Vuillemin. 
Mann, H. H. and C. M. Hutchinson. Cephaleuros virescens, Kunze, 
the ‘red rust’ of tea. (Mem. Depart. Agric. India Bot Ser. 
Vol. I. N°. 6. p. 1-35. Plates I—VIII, 1907.) 
This alga (family Chroolepidae) which is parasitic on the tea 
plant is now regarded as a serious disease in N. E. India, and 
since 1901 has been under continuous Observation. It occurs on the 
tea bush in two easily recognised forms — as a usually epiphyllous 
development on the leaves, and as an endophyte in the cortical 
tissues of the stem, the latter being the dangerous form. The fruc- 
tifying cellular hairs bearing the sporangia appear about March or 
April, forming red isolated patches on the remains of the previous 
year’s wood. After this the leaves of the affected shoots become 
more or less completely chlorosed, and death cf the shoots usually 
ensues. If the disease is not checked the whole bush gradually 
becomes involved and perishes. Two definite forms of reproductive 
organs occur haken-sporangia, borne at the extremities of delicate 
tubulär septate filaments, and kugel-sporangia, which are embed- 
ded in the mass of the algal thallus and only occur in the epiphyl¬ 
lous form of the blight, never on the stem. Propagation takes place 
either by zoospores, which are carried by water after expulsion 
from the sporangia or the sporangia as a whole may be carried by 
wind to the position where they are to grow. The attack of young 
tea stems is intimately connected with their rough surfaces, and 
there is also a direct connection between the spread of the blight 
and the want of vitality in the tea plants attacked. 
VV. E. Brenchley. 
Mc. Alpine, D., The nature and aims of plant pathology. 
(Agric. Gaz. New S. Wales. Vol. XVIII. p. 193—206. 1907.) 
The author gives a short historical resume of the growth of 
Plant Pathology as a Science, and draws a comparison between 
Animal and Plant Pathology. Arnong the chief problems to be dealt 
with at the present day are those associated with the Rust and Smut 
