ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 483 



spread of such a disease, as for several years it had been known in dis- 

 tricts near. The author also comments on the oak mildew : only the 

 conidial form was found, no perithecia, though they were diligently 

 looked for. He discusses the name and affinities of the fungus, and 

 does not consider it to be identical with Thumen's Oklium quercinum. 



Stroma-formation in Xylaria Hypoxylon.* — D. Linford Freeman 

 has grown the stromata of this fungus in various substrata and in vary- 

 ing conditions to test the factors that influence their growth. As culture 

 media, wood, gelatin, and agar were used successfully ; sand soaked in 

 culture solutions did not give good results. Freeman secured germina- 

 tion of ascospores, but not of conidiospores. He describes the develop- 

 ment of mycelia and stromata on agar, and compares the influence of light 

 and darkness ; in the latter condition, though the mycelium developed 

 well, the stromata were small. Light acted favourably on the growth of 

 the stromata, and they were proved to be positively heliotropic. The 

 changes induced by wounding the stromata are fully described ; very 

 irregular branching was provoked by this means. Another phenomenon 

 noted was the growing together of neighbouring stromata, especially at 

 the apex. 



Critical Notes on Yeast Researches.f — A. Guillierrnond reviews the 

 recent literature on this subject, and draws up a series of pronounce- 

 ments of his own opinions and conclusions. 1. The nucleus of the 

 yeast-cell always divides by amitosis during budding. 2. The yeast- 

 nucleus consists of colourless nucleo-hyaloplasm surrounded by a coloured 

 membrane. It contains a large nucleolus and a chromatic framework. 

 3. The yeast-cell contains two series of secretory grains : metachromatic 

 corpuscles lodged in the vacuoles, and granules stained by iron-haBinato- 

 xylin which are dispersed through the protoplasm, and are called by 

 Guilliermond " basophil grains." They are probably albuminoid bodies, 

 products of nutrition. 4. It has not been possible to observe nuclear 

 division in the ascus, but probably it is mitotic. 5. The epiplasm of 

 the ascus contains large quantities of glycogen, fats, and metachromatic 

 corpuscles which constitute a reserve necessary for the formation of the 

 spores. 6. There is no extra-sporal nucleus in the epiplasm. 7. There 

 has been observed, in the conjugation of the spores in the Yeast Johan- 

 nisberg II., certain figures where the two nuclei remain in contact and 

 seem to divide simultaneously by amitosis during the budding of the 

 zygospore, becoming united only in later cells as if there had been a 

 synkarion formation. 



In a final note the author denies the correctness of Wager's and 

 Peniston's views as to the structure of the yeast-nucleus, and gives his 

 reasons for dissenting from their conclusions. 



Hyphomycetes.J — in this recent fascicle G. Lindau continues his 

 study of revised forms. A large number of species, described in recent 

 years, are added, and notes given referring to new habitats or to de- 

 scriptions not already included. A number of new genera have been 

 added, and these are published with descriptions and figures. 



* Ann. Mycol., viii. (1910) pp. 192-211 (14 figs.). 



t Ccntralbl. Bakt., xxvi. (1909) pp. 577-89 (G figs.). 



I TCabonhorst's Krypt. Flora, 9^ Abt., Lief. 117 (Leipzig, 1910) pp. 153 816. 



2 K 2 



