Mj'xomycetes. — Pflanzenkrankheiten. 463 



of systematic mycologists, especially in connection with Ihe Myce- 

 tosoa, from the earliest references to these organisms down to the 

 work of De Bary and his pupils. Notes are added on the lives of 

 some of the chief investigators. E. M. Wakefield (Kew). 



Brooks, J. T., Silver-Leaf Disease. (II). (Journ. Agric. Sei. 

 V. 3. p. 288-308. June 1913.) 



The author gives an account of observations and experiments 

 made since the publication of his first paper in 1911. Additional 

 evidence is brought forward showing that silvering in fruit trees is 

 frequently caused by the fungus Stereurn purpureum, acting as a 

 wound-parasite. Inoculations with portions of sporophores obtained 

 from a dead Birch stump produced the disease quite as badly as 

 those with sporophores obtained from plum. No silvering was pro- 

 duced on inoculation wüth St. hirsutum, St. rugosum, and Polystictus 

 hirsutus. 



On the other hand, certain cases of silvering, such as that of 

 seedling plums, and of Lamium album, cannot be due to St. pur- 

 pureum. 



The author concludes that Silver-Leaf is a general pathological 

 phenomenon which may be caused in various ways. It is possibly 

 due to a disturbance of the transpiration current, and its manifesta- 

 tion appears to depend partly on leaf-structure. Apples and Cherries 

 may be killed b}^ St. purpureum without showing silvered foliage. 



E. M. Wakefield (Kew). 



Caylcy, D. M., A Preliminary Note on a New Bacterial 

 Disease of Pisum sativum. (Proc. Roy. Soc. Ser. B. LXXXVI. 

 586. p. 171 — 173. 1913.) 



The note deals brie'fly with a disease of peas w^hich is attributed 

 to a large bacillus transmitted in the interior of the seeds. The 

 organism^ occurs in the phloem, cambium, medullary rays, and 

 occasionally in the pith of the stem; in the parenchyma of the vas- 

 cular bundles running along the midrib of the pod, and in the 

 tissue of the funicle and cotyledons. The disease is characterised 

 chiefly by the appearance of light brown longitudinal streaks, which 

 later become splits. These occur on the stem and root at an early 

 stage, and later at the base of the petioles. In cases of mild attack, 

 the plant may flower and set seed, and the bacillus passes into the 

 young developing seeds. In bad cases little or no germination 

 takes place. 



Similar bacteria have been found in the stem of sweet peas 

 attacked by "streak", and the author considers it doubtful whether 

 this disease is in reality due to Thielavia basicola. 



E. M. Wakefield (Kew). 



Dowson, W. J., On a Disease of Greengage Trees caused 

 by Dermatella prunastrij Pers. (New Phytologist. XII. 6. p. 207— 



216. 1913 



A "die-back" of greengage trees is caused by the fungus Der- 

 matella prunastri, Pers. Other plum trees are rarely attacked. The 

 mycelium is found in all the tissues of the stem, and particularly 

 in" the wood and pith. The hyphae pass from one cell to another 



