410 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the fungus is cultivated on a large scale. The mature cultures are then 

 dusted over with starch or flour, and the dry powder is spread with 

 dusting machines over the areas infested bv froghoppers. Good results 

 are confidently expected. 



Fundus Succession.* — W. H. Brown and P. W. Graff found from 

 observation and experience in Manila that a regular succession of fungi 

 appeared on dung : first Mucors followed by Oospora, which both died 

 down in about ten days, finally the sporophores of Goprini, which were 

 produced over a considerable period. The order in which these fungi 

 appear is caused by the different rates of development and growth from 

 the spores contained in the dung. They concluded that the early dis- 

 appearance of the mould fungi was due to micro-organisms. Mucor 

 persisted for a long time on sterilized material, and even appeared 

 vigorous after the substratum seemed to have dried up. Toxins also may 

 have been formed by the fungi, but not in quantity sufficient to account 

 for the succession. 



Mycorhiza.f — W. Magnus, in the text accompanying the illustrations 

 of mycorhiza formations, has given a general review of the whole subject. 

 In the first part, which deals with ectotrophic mycorhiza, especially of 

 Conifers, he finds a fungus-mantle fairly constant on the roots, though 

 it sometimes is wanting. He describes the antagonistic development 

 of roots and of fungi ; there is no mutualistic symbiosis, he considers, 

 in the Abietinese, but perhaps an adaptation to the influence of the 

 fungus. 



Under endotrophic mycorhiza he discusses the formations on the 

 roots of orchids, and the significance of the fungus to these plants. He 

 thinks that through the action of the fungus on the roots of Neottia 

 Nidus-avis the latter is enabled to use material from the substratum 

 that ordinarily the higher plants cannot take up. 



Plant Diseases. — C. W. Edgerton % describes a disease of sugar-cane 

 caused by a fungus known as Gnomonia iliau, first described in Hawaii. 

 The disease is especially virulent in a cool season, as the cane is then less 

 able to resist an attack. The cane is attacked in the earlier stages of 

 growth, and the fungus fruits towards the fall of the year. An im- 

 perfect stage, Melancomym iliau^ has also been discovered, generally 

 in the outer leaf -sheaths, but also in those more deeply covered. The 

 perithecia have hard beaks, which emerge some distance from the surface, 

 and the whole leaf where they grow becomes rough with them. 



J. R. Weir § has published observations on Polyporus BerkUyi, a 

 stalked form which he found occurring at the base of larch-trees. It 

 has the ability to spread its mycelium as a wound-parasite in parts of the 

 tree injured by squirrels, fire, etc. There is no evidence that it attacks 

 living wood, but it destroys dead wood, bringing about a white rot. 



* Philippine Journ. Sci., viii. Sec. C, i. (1913) pp. 21-9. 



t Bot. Wandtafeln, mit erlautertem Text. Berlin : L. Kny (1911) xiii. Abt. 

 See also Zeitschr. Bot., v. ^1913) pp. 406-7. 

 X Phytopath., iii. (1913) pp. 93-7 (1 pi.). 

 § Phytopath., iii. (1913) pp. 101-4 (1 pL). 



