338 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and in America. He finds that there are two physiological forms of the 

 same fungus. The American form causes more serious disease, as it 

 attacks the fruit at an earlier stage ; it also attacks living shoots, causing 

 canker. The European fungus is not known to cause canker. The 

 morphological differences between the two forms are very slight. 



Species of Penicillium.* — R. Westling has collected and cultivated 

 a large series of Penicillium forms. He holds that physiological as well 

 as morphological characters should be described in any diagnosis. He 

 has united Citromyces with Penicillium. He deals with forty-four dif- 

 ferent green species, of which sixteen are new. He gives data as to the 

 most suitable media on which to grow these moulds. 



Wintering of Monilia Spores. t — R. Ewert-Proskau has made a. 

 series of experiments with mummified fruits on which he found tufts 

 of 3fmiilia. He found that the spores of M. cinerea could persist through 

 the winter on the mummified sweet or sour cherries, and also on plums, 

 and that they were good for germination at any period. The spores of 

 M.fnictigena\o9,Q\X\Q\Y germinating capacity usually before the begin- 

 ning of the winter season. As M. cinerea easily forms new tufts of 

 conidiophores in moist warmth, it is always in a condition to infect new 

 growths, and thus more readily attacks early flowering stone fruits than 

 the more slow-growing M.fructigena. The difference in wintering pro- 

 perties between the two species must be considered as biological, and is 

 not due alone to the power of resisting extreme cold, as that is shared to 

 a certain extent by both fungi. 



Influence of Uromyces Pisi on Euphorbia Cyparissias.| — (x. 

 Tischler opens his discussion on this subject l»y a short account of 

 gall-formations. He also states that he had noticed that young shoots 

 of the Euphorbia were free from the malformations caused by the 

 fungus. Especially was this the case in some plants in a moist valley 

 in the Northern Vosges. They were deformed in the lower parts, the 

 leaves being much thickened, while the upper shoots and leaves were 

 normal in appearance. By experiments in damp chambers he found 

 that the moist conditions favoured the growth of the host but not of 

 the fungus. 



As a rule the mycelium pervades the plant up to the apex, but so 

 long as the individual cells are quite filled with plasm no haustoria 

 enter them ; only when vacuoles arise does the mycelium penetrate the 

 cells. The hyphfe, however, may be found in the intercellular spaces 

 close to the growing points. Apices that are free from the fungus 

 generally remain so. It has been found that the fungus increases 

 rapidly in the winter buds, and this because the hyphs enter the 

 vessels, though haustoria are not developed there nor is the cambium 

 ever attacked. 



The changes induced in Euphorhia by fungus infection are an 

 alteration in the form of the cells, more active cell-division, and an 

 enlargement of the intercellular spaces. For a considerable time the 



* 



Ark. Bot., xi. 1 (1911) 156 pp. (81 figs.). See also Ann. Mycol., x. (1912) p. 99. 

 t Zeitschr. Pflanzenkr.,xxii. (1912) pp. 65-86. 

 X Flora, civ. (1911) pp. 1-60. 



