360 REPORT— 1897. 



have named Aecidium Jacobsthalii, Henrici, and I consider that the Aecidium 

 mageUanicum observed by Berkeley on Berberis ilicifolia should be distinguished 

 from the two abore-mentioned aecidia. 



The fungus causing the witches' broom on the barbery in Europe should there- 

 fore no longer be called Aecidium mageUanicum, Berk., but must be called either 

 Aecidium graveolens, Shuttlew., or aecidium form of Puccinia Arrhenatheri (Kleb.), 

 Erikss. 



4. Stereum hirsutum, a Wood-destroying Fungus. By H. Marshall Ward, 

 D.Sc, F.S.S., Professor of Botany in the University of Cambridge. 



The author has cultivated this fungus from the spores, on sterilised wood 

 blocks, and has not only obtained very vigorous pure cultures, and traced the action 

 of the mycelium week by week on the elements of the wood, but has obtained 

 spore-bearing hymenia, and worked out the life-history very completely. Hartig, 

 in his ' Zersetzungserscheinungen des Holzes,' examined the wood-destroying action 

 of this fungus, but used material growing in the open, and therefore not pure. 

 Brefeld attempted its culture, but failed to make it develop any fructification or 

 spores ; since Brefeld does not allow us to know the composition of his media, it 

 is not possible to suggest why he failed. 



The fertile hymenium arises in about three to four months, and the author has 

 examined the development very thoroughly, and refers to discrepancies in the 

 existing descriptions. The details of its destruction of the wood are also gone into 

 fully ; the fungus delignifies the inner layers of the walls of the wood-elements, 

 and in three months' cultures and upwards these turn blue in chlor-zinc-iodine, 

 and are shown by other reagents to undergo alteration to cellulose-like bodies 

 before their final consumption by the fungus. 



Drawings and lantern slides made by Mr. Ellis from the author's preparations 

 were shown. 



5. The Nticleus of the Yeast Plant, By Harold Wager. 



Of the numerous observers, some twenty in number, who have made observa- 

 tions upon the presence of a nucleus in the yeast plant three only actually deny 

 its existence. Many conflicting statements, however, have been made as to its 

 nature, some observers having described it as a perfectly homogeneous body, others 

 as possessing a nuclear membrane and nucleolus, whilst two observers regard cer- 

 tain granules present in the cell under certain conditions as of the nature of a 

 nucleus. 



In Saccharomyces cereviseee the nucleus can be easily demonstrated by careful 

 staining in hsematoxylin, Hartog's double stain of nigrosin and carmine, or by 

 staining in aniline-water solution of gentian violet. It appears to consist, in the 

 majority of cases, of a homogeneous substance, spherical in shape, placed between 

 the cell wall and the vacuole. By very careful staining, however, and especially 

 after digestion in pepsin glycerine solution, a granular structure can be observed. 

 The whole cell is in the normal, imdigested state, often pervaded by such a deeply 

 stainable substance that this granular structure is difficult to make out. On the 

 whole, perhaps, it resembles more than anything else the fragmenting nuclei in the 

 older leaf cells of Chara ; that is, it consists of deeply stained granules embedded in 

 a slightly less stainable matrix. These granules are probably chromatin granules, 

 and the matrix occasionally gives evidence of a slight granular structure. 



The process of budding in a yeast cell is accompanied by the division of this 

 nucleus into two. The division is a direct one, and does not take place in the 

 mother cell, but in the neck joining it to the daughter cell. When about to divide, 

 the nucleus places itself just at the opening of this neck, and proceeds to make its 

 way through it into the daughter cell, until about half of it has passed through, 

 when it divides completely, and the two nuclei thus formed separate from each 

 ffither towards the opposite sides of their respective cells. 



