410 SUMMARY" OF CURRENT RESEARCHES RELATING TO 



" hyf)ostroma." Intermediate forms have shown that such an arrange- 

 ment is not a natural one. Arnaud has recognized two main groups : — 

 (1) Protothyrieae, represented by Protothyrium g. n., in which there is no 

 true perithecium ; and (2) Eumkrothyriese, in which the asci occur in 

 chambers in a sti'oma. Stoloniferous or fumagine Microthyriaceas are 

 most common in the rainy tropical districts. Most of them are recog- 

 nizable at the first appearance of the fungus by their radiate habit of ^ 

 growth. 



Prevalence of Endothia gyrosa.* — An examination has been made 

 by Neil E. Stevens of the conditions affecting the distribution of this 

 fungus, which is not always co-extensive with its host-plants. It is an 

 indigenous parasite, and was recorded by Schweinitz about a century ago, 

 but though widespread it is abundant only in the South-Eastern States. 

 It attacks hosts belonging to four genera, Gastanea, Fagus, Liquidambar 

 and Querciis, the latter the most abundantly. The temperature of the 

 Southern States is that most favourable to its development and continu- 

 ance, but under certain conditions it will winter further north. 



Water-supply and the condition of the host are important factors, 

 and it grows most readily on injured tissues, such as stubs of cut limbs 

 or injured roots. One of the most important agents in securing the 

 greater abundance of the parasite was the increase of opportunity of 

 infection, and that condition prevails in the south, where the host species 

 are more numerous. Injury and exposure of hosts by erosion or by 

 cultural conditions are also aids to attack by the fungus. 



Uredinese. — E. B. Mainsf records the first discoveries of Melampsora 

 on Eupliorbria in the Western Hemisphere. Of these, one upon E. 

 cyparissins from Maine had been introduced, but species on E. commutaia 

 from Indiana and on E. rohusta from Colorado and Wyoming are native. 

 The one on E. rohusta is a new species, M. monticola ; the others have 

 already been described, and are European species. 



J. R. Weir and E. E. Hubert^ record the results of a series of 

 Uredine inoculations. They have decided that the various caulicolous 

 forms of rust on Piniis contorta and P. ponderosa are the eecidial stages 

 of Cronarlium coleosporoides. Experiments were carried out with 

 secidiospores pf Cronartium Gomptonise from Pinus Banksiana on Gomp- 

 tonia asplenifoUa, and uredinia were formed. Uredinia were also 

 developed on Myrica carolinensis and on M. Gale. A number of cultures 

 were also made with Melampsorae on Popidus and on Larix with 

 successful results. 



The same ^^riters§ also^report an abundant growth of pycnospores 

 of Gronartiuni coleosporoides on Pinus ponderosa, which exuded from the 

 pycnidia in September in Montana, thus proving that their production 

 is not confined to Spring months. The exudations consisted of a clear 



* Bull. Torrey Bot. Club, xliv. (1917) pp. 125-44. 



t Phytopathology, vii. (1917) pp. 101-5. 



X Phytopathology, vii. (1917) pp. 101-9. 



§ Phytopathology, vii. (1917) pp. 135-9 (2 figs.). 



