ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 663 



Mycorhiza of the Beech.* — Dr. P. E. Miiller confirms Frank's ob- 

 servations | with regard to the mycorhiza on the young roots of the 

 beech. He finds it especially in dry sandy soil exposed to the sun, 

 where there are few earthworms, and where the soil has in conse- 

 quence become exceedingly compact and hard. In such situations the 

 lower roots of the beech trees die off, and they are nourished entirely 

 by a reticulation of smaller roots near the surface. The ground 

 becomes covered with a layer of dead leaves which is converted into 

 humus by the attacks of fungi, rhizopods, &c. The finer roots of the 

 beeches gradually approach the surface, and at length penetrate this 

 layer, and the fungus-mycelium with which they become invested acts 

 as a saprophyte, and conveys to its host the soluble humates and other 

 substances formed in the layer of decaying vegetable matter. 



Vitality of Spores of Parasitic Fungi.J — Dr. A. B. Griffiths has 

 experimented in the following manner : A quantity of spores of 

 Peronospora infestans (potato-disease) were taken from a crop of 

 diseased potatoes. These spores were then placed in a porcelain 

 mortar along with about 5 grms. of a mixture of calcium sulphate and 

 calcium carbonate, which were thoroughly mixed together. This 

 mixture was then placed in a small oven always kept at a temperature 

 of 35° C. (dry heat). After the spores had been dried up with these 

 mineral substances (which principally constitute the dust found in 

 the atmosphere) for two months, they had not lost their vitality, for 

 in the space of three days after " sowing " they began to penetrate 

 into the mesophyll of the leaves (of a potato plant) through the 

 stomata. The leaves of Solanum tuberosum, along with dried two 

 months' old spores of Peronospora, were kept in a warm, moist atmo- 

 sphere, such conditions being favourable for the development of these 

 spores. On the fifth day after " sowing " there was a mycelium 

 which had ramified through the tissue of the leaf, and there was 

 also observed the production of conidia-bearing branches making 

 their appearance through the stomata of the leaves. After six months 

 of dry heat another portion of the dust was examined under the 

 Microscope, mounted in water as before. The cellulose wall of the 

 spores appeared rather shrivelled. Their vitality had not disappeared, 

 for after seven days from " sowing " on the potato leaf there was a 

 rapid development of hyphaa, &c. ; thus showing that even after the 

 spores had been dried up for six months as dust, they were capable of 

 germinating, and each organism leaving its life-history upon the 

 host-plant. 



Again, after being in a dried ,tate for ten months, it was found 

 that the spores had lost their vitality. They did not germinate upon 

 the leaves of Solanum, not after being in contact with the leaves in 

 a warm and a damp atmosphere for a month or six weeks. Under 

 the Microscope the spores were seen to be shrivelled up and their 

 protoplasm dead. 



* Bot. Centralbl., xxvi. (188G) pp. 22-6 (5 figs.). 



t See this Journal, v. (1885) p. 844. % Chem. News, liii. (1886) pp. 255-7. 



