:80 SUMMARY OF CURRENT RESEARCHES RELATING TO 



issue explosively, and are then carried away by rain or dew. The writer 

 •describes the changes that take place in the ascus, and compares spore 

 discharge in this fungus with others. 



Spegazzinian Meliola Types.* — F. L. Stevens has received a number 

 ■of packages containing Spegazzini's types, descriptions and drawings 

 of MelioJa. He has had the drawings carefully copied and compared 

 with the type material, and he now publishes them, with references to 

 the original publication. There is a long list of these species. Stevens 

 values very highly the work Spegazzini has done, and desires to 

 emphasize the great indebtedness of mycology to his careful work. 



Infection by Cercospora beticola.f — V. W. Pool and M. B. McKay 

 have made a study of the leaf infection by this fungus with reference 

 to penetration by the germ-tubes of the stomatal opening. For this 

 purpose they have made a prolonged study of the beet stomata, and have 

 stated the various conditions influencing stomatal movements, and there- 

 fore infection. Penetration occurs only through open stomata, and 

 most frequently on mature leaves. Infection probably takes place 

 during the day-hours. The fungus forms a dense mycelium in the 

 air-chamber below the stoma ; it then grows towards the parenchyma 

 cells and flattens out against their walls. It may immediately grow out 

 again by the pore and form conidia, but usually it penetrates deeper. 

 The host -cells may mass material and remain turgid, thus isolating the 

 invading parasite, but usually they collapse and allow its further growth. 



Septoria Chenopodii.J — W. B. Grove publishes an account of the 

 synonymy of this fungus, which is large and varied. The differences in 

 view have arisen primarily from the spore conditions. They are for a 

 long time simple, in which condition the fungus has been naturally 

 classified under PhijllosUcta. In time the spores become one or more 

 septate, and have been placed in other genera. The species was found in 

 this country by M. C. Cooke at Holloway. It has since been found on 

 Chenopodiwn and on Atnplex at various other localities. Grove adds a 

 variety emaculata when it occurs on stems without any distinct " spots " 

 Toeing formed. 



Factors involved in the Growth of Pycnidia.§— G. H. Coons has 

 made a large series of cultures of the fungus Pletiodomus fascomaculans 

 to determine the conditions that favour pycnidial formation or the 

 reverse. He employed a great variety of media, chemical and others, 

 and took note of temperature and light conditions. The difl'erent results 

 obtained in the various foods supplied were due to their acid or alkaline 

 nature. Aeration is essential for reproduction. Pycnidia were only 

 found in cultures exposed to light ; the ordinary room temperatures 

 were sufficient. 



* Bot. Gaz., Ixiv. (1917) pp. 421-5 (3 pls.)." 



t Journ. Agric. Eesearch, v. (1916) pp. 1011-38 (2 pis.). 



: Journ. Bot., Iv. (1917) pp. 346-8. 



§ Journ. Agric. Research, v. (1916) pp. 713-69. 



