ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 157 



comparatively free from the bli^rlit numbers of potatoes are stored and 

 pitted that are very slightly affected, and these may develop and sa 

 produce a. bad pitting season. The result of planting diseased tubers 

 was noted, and it was found that only about half of them develop, but 

 in no instance was it found that they became a centre of infection, 

 though probably in many cases they do give rise to epidemics of the 

 disease. Hibernation of the mycelium in the tubers is, so far as is at 

 present known, the only way in which the blight fungus survives from 

 one season to the next. 



The ravages due to the stalk-disease, Sclerotinia libertiana, and of a 

 leaf-disease due to Bohrytis cinerea are described ; both of these have a 

 sclerotium stage. Another troublesome disease somewhat similar in its 

 effect to black-stalk rot is caused by a hyphomycetous fungus, Verti- 

 cilHuin alboatrum. The mycelium of the fungus penetrates into the 

 water-conducting tissues of the plants, choking them and thus causing 

 withering and death. When the stalks are dead, the fungus spreads 

 from the wood vessels into the neighbouring tissues, then passes into a 

 resting condition and turns black. 



The collar fungus, Hijpochnus Solaiii, has also been investigated. 

 It was formerly known as Rhizoctonia Solani. It is fairly prevalent, 

 but in Ireland it does not seem to cause any serious disease. 



C. W. Edgerton * describes his method of securing disease-resistant 

 tomatoes. He grew immbers of plants on soil that had been first 

 sterilized, then heavily infected with Fusarium Lycopersici, the wilt 

 fungus. Most of the plants took the disease seriously : those that 

 escaped were used for further cultivation in normal soil and proved to 

 be largely resistant to the disease. 



A. Trotter t has found chestnut-trees badly infested with Oidium 

 Querri/s in Italy ; it has also been reported on beech-trees by Farneti in 

 the Bolognese Appennines. Trotter therefore concludes that the possible 

 affinities of the fungus are enlarged if its identity with Microsphsera 

 quercina and with M. alphUoides be not accepted. The special virulence 

 of the attack was due to the formation of new shoots on trees felled out 

 of season in the early part of July. The new shoots, sprouting about 

 the middle of August, developed with difficulty, and were consequently 

 in a highly receptive condition. 



J. M. Murray % signals the destructive character of Polyporus Schivei- 

 nitzii in Scotch woods. It was found attacking Douglas fir and Sitka 

 spruce in Perthshire, and Scots pine in Midlothian. It has also l)een 

 recorded on larch in England. The mycelium changes the wood to a 

 dull yellow colour, finally to dark brown, while here and there small 

 packets of white mycelium are visible. The whole mass becomes 

 brittle and has a turpentine odour. Eemedies are suggested. 



* Science, n.s. xlii. No. 1095 (1915) pp. 914-5. See also Bull. Agric. Intell. 

 Rome, vii. (1916) pp. 751-2. 



t L'Alp, ser. 2, iii. No. 2 (191G) pp. 49-53. See also Bull. Agric. Intell. Rome, 

 vii. (1916) pp. 758-9. 



X Trans. Scott. Arbor. Soc, xxx. pt. 1 (1916) pp. 56-7 (1 pi.). See also Bull. 

 Agric. Intell. Rome, vii. (1916) p. 759. 



