ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 441 



the infection powers of the ascopores have been proved to be strictly 

 similar to those of the oidia. Special economic interest is attached to 

 experiments with hop-mildew. The fungus which causes this disease, 

 Sphmrotheca Humuli, grows on a variety of different plants ; but it was 

 found that it was specialised on each host, and could not be transferred 

 from one to the other. Again, in the case of E. Cichoracearum, conidia 

 collected from Plantago major infected P. major, producing an abundant 

 crop of oidia and perithecia, while on P. media there was mostly only a 

 feeble sub-infection, and P. lanceolata was immune. The author gives 

 detailed tables of the various experiments. 



Mycological Notes.* — E. S. Salmon finds that the asci of Erysiphe 

 graminis do not form spores until the conditions of moisture, etc., are 

 favourable for their subsequent germination and development. He 

 tested this repeatedly in the laboratory, aud found that in a damp 

 chamber the spores matured quickly, were ejected from the perithecium 

 and at once germinated. He infected leaves of Tritkum vulgare, and 

 in about ten days powdery Oidium -patches were observed on the grass. 

 He thinks the fungi may go through the life-cycle more than once 

 in the course of the season. He adds some notes on the mycophagus 

 larva? that feed on the conidia, and which doubtless aid in checking the 

 spread of the fungus. 



Observations on G-ymnoascaceae and Aspergulese.f — P. A. Dangeard 

 publishes notes on the question of sexuality in the genera and species 

 of these fungi. He records the occurrence of the two coiled cells in 

 the early stage of fruit formation in species belonging to Ctenomyces, 

 Gymnoascus and Aphanoascus. He denies that sexual fusion takes 

 place. In Aphanoascus, the most easily observed, the sterile cell becomes 

 large and spherical, enclosing four or five nuclei, which increase to about 

 forty. The nuclei of the ascogonial cell also increase. This cell winds 

 round the central sterile cell, and then gives rise to five or six branches, 

 which also encircle it, and these branches divide into isodiametric cells. 

 There never is any trace of anastomosis or of fusion to be observed be- 

 tween the two organs. 



l &' 



Yeast Nucleus.^ — A. Guilliermond reviews the work done by him- 

 self and others on Saccharomyces. He insists on the correctness of 

 his statements as to the existence of a vacuole with metachromatic 

 corpuscles, and a nucleus close by — the nucleolus of Wager. He also 

 insists on the existence of only one nucleus in the sporulating cell. 

 He describes the division of this nucleus into two or four daughter- 

 nuclei previous to sporulation — a division first into two masses which 

 emigrate to the two poles, and then divide again in the same manner. 

 He has never seen any case of karyokinesis. The achromatic spindle 

 seen by Janssens and Leblanc is only " sporogenous plasma." He noted, 

 further, that the epiplasm of the cell contained small oil-globules, which 

 in this case are reserve bodies. 



* Journ. Bot., xlii. (1904) pp. 1S2-6. 



+ Comptes Bendus, exxxviii. (1904) pp. 1235-7. 



\ Ann. Mycol., ii. (1904) pp. 184-9 (1 fig.). 



