Gelehrte Gesellschaften. — Instrumente etc. 31Q 



thum der genannten Luftwurzeln bis zu einem Optimum (L. im 

 Mittel = Vs), um mit weitersteigender Lichtintensität bei einem 

 Lichtmaximum (L. im Mittel = 1 J2.s) zu erloschen. 



Congresse. 



Meeting of the British Association, Liverpool. 



Vortrag vom 14. September 1896. 



P. Magnus: 



On some Species of the Chytridiaceous Genus Uropldyctis. 

 The author maintains the genus Uropldyctis, established by 

 J. Schroeter, in Opposition to the opinion of AI fr ed Fis eher. H 

 describes the development of the species Urophlyctis Kriegeriana, 

 oecuring in Cavum carvi, established by bim some years ago, and 

 shows that its spores are formed by the conjugation of two cells, 

 arising from difFerent filaments, and lhat the development of the 

 fungus takes place within a single cell of the host, namely, the 

 central cell of the gall produced by it, which is of limited growth. 

 The author proves that the fungus observed by Trabut in Algiers, 

 which causes large swelling on beetroots, also belongs to this genus 

 Uropldyctis. It was described by T r a b u t and also bySaccardo and 

 Mattirolo as one of the Ustilagineae {Oedomyces leproides Trab.). 

 The author proves that its spores are likewise formed by the 

 conjugation of two Celles, arising from different filaments, exactly 

 as in Uropldyctis. While these observers State that the fungus 

 developes in individual cells of the tumours caused by it, the 

 author shows that the cells containing the fungus are connected 

 with one another by canals of variable length and width, and that 

 hence the cells containing the fungus are only outgrowths and 

 branches of one and the same cell. The species only difFerts from 

 Urophlyctis Kriegeriana in the unlimited growth of the gall, which 

 corresponds to the continued ramification of the cell attacked by 

 the fungus. 



Finally, the author deals with the devolopment of the gall of 

 Urophlyctis pulposa, which differs from that of the species already 

 described. 



Instrumente, Präparations- und Conservations- 



Methoden. 



Strasburges E., Das botanische Practicum. Anleitung zum Selbststudium 

 der mikroskopischen Botanik. Für Anfänger und Geübtere. Zugleich ein 

 Handbuch der mikroskopischen Technik. 3. Aufl. gr. 8°. XLVIII, 739 pp. 

 Mit 221 Holzschnitten. Jena (Gustav Fischer) 1897. M. 20.—, geb. 22.50. 



