ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 629 



constantly found just beneath the cuticle ; in other forms it goes deeper 

 into the tissue, as in Guignardia, Fusarium, Vmturia, and Marsonia. In 

 Mycetoderma the tissues are only invaded when the leaves are dead ; 

 Fusicladium pyrinum and F. dendriticum are subcuticular in the leaf, but 

 penetrate more deeply in fruit or branch. Many other points of interest 

 are entered on in the memoir : action of the fungus on the host, form of 

 the thallus, etc. Some new species have been discovered, and are 

 described. 



Blue Disease of Pine-wood.* — ■ The blue colour is stated by E. 

 Munch to be due to a light-effect on finely divided mycelium, and not 

 to any colour produced. The disease is caused by a species of a 

 Pyrenomycete, Ceratostomella, a composite species which includes several, 

 distinguished from each other more particularly by their conidial form — 

 in some being a species of Cladosporium, in others a Graph i am or 

 Ghalara I 'iigeri. The author also describes a species of Cladosporium on 

 pine-wood which induced a blue coloration, but he did not find any 

 higher fruiting form connected with it. 



In a further paper f the author discusses the biological conditions 

 that affect the growth of the parasite. It does not grow except in the 

 presence of a certain amount of air, and increases rapidly when the air is 

 also increased by disappearance of the sap, etc. 



Diseases of Plants. — E. S. Salmon % describes the nature and extent 

 of the disease of apple-leaves and fruit caused by a fungus, Fusicladium 

 dendriticum, and known as "apple scab" or "black spot," which first 

 becomes noticeable by the damage it causes to the young fruit. On the 

 leaves, the fungus is usually to be found on the upper surface, where it 

 forms black patches. It also occurs on the young wood of the tree, 

 producing a blistered appearance. The disease can be checked and 

 controlled by systematic spraying with Bordeaux mixture, the first 

 application of which should be on the young unfolding leaves, just 

 lief ore the blossoms open. If the wood has been attacked, it should be 

 cut out as much as possible, and the tree sprayed during the winter. 



Several cases of fungus disease are reported in the same § journal : 

 Anemones from Penryn were attacked by rust, peaches from Ilminster 

 were injured by leaf-curl, Exoascus deformans, and the roots of youug 

 peas from Cher'tsey were attacked by Thielavia basicola, a fungus which 

 spreads very quickly under favourable weather conditions. Remedies are 

 suggested for these diseases. 



' Kirchner |] has conducted a series of experiments by artificial inocu- 

 lation of wheat with Tilletia Tritici— drawing a parallel between the 

 germinating force and the liability to infection. In summer wheat, the 

 greater the f oree the less danger there is of the disease ; but this does 

 not hold good for the common winter wheat, as the results there prove 

 exactly the opposite. 



* Nat. Zeitschr. Land.-Forstw., v. (1907) pp. 531-73. See also Bot. Centialbl., 

 cvii. (190S) pp. 275-6. 



+ Op. cit., vi. (1908) pp. 32-47. See also Bot. Centralbl., cvii. (1908) p. 515. 



t Journ. Board Agric, xv. (1908) pp. 182-95 (9 rigs.). 



§ Tom. cit. p. 203. 



I! Fiibling's Landw. Zeit., 1908, p. 161. See also Ann. Mycol., vi. (190S) pp. 

 168-9. 



