Bd. XCVI. Nr. 17. XXV. Jahrgang. 



Botanisches Centralblatt. 



Referirendes Organ 



der 



Association Internationale des Botanistes 



für das Gesammtgebiet der Botanik. 



Herausgegeben unter der Leitung 

 des Präsidenten : des Vice-Präsidenten : des Secretärs : 



Prof. Dr. K. Goebei. Prof. Dr. F. 0. Bower. Dr. J. P. Lolsy. 



und der Redactions-Comtnlssions-Mitglieder : 



Prof. Dr. Ch. FSahault und Dr. Wm. Trelease. 



von zahlreichen Specialredacteuren in den verschiedenen Ländern. 

 Dr. i. P. Lotsy, Chefredacteur 



No. 43. 



Abonnement für das halbe Jahr 14 Mark 

 durch alle Buchhandlungen und Postanstalten. 



1904, 



Alle für die Redaction bestimmten Sendungen sind zu richten an Herrn 

 Dr. J. P. LOTSY, Chefredacteur, Leiden (Holland), Rijn-en Schiekade 113. 



Blackman, V. H., On the f er t ilisati on, altern a t i o n o f 

 generations, and general cytology of the Uredi- 

 neae. (Annais of Botany. Vol. XVIII. p. 323—374. With 

 plates XXI— XXIV.) 



The author has made a füll and careful study of the deve- 

 lopment and the cytology of two members of the Ureclineae, 

 viz. Phragmldlum vlolaceum and Gymnosporangium clavarlae- 

 forme. The results thus obtained have thrown much light on 

 the significance of the more important features of this group 

 of fungi, the homologies of which have hitherto been very 

 obscure. 



It has been known, since the researches of Sapin- 

 Trouffy, Poirault, and others, that the aecidiospores and 

 the uredo- and teleuto-generations are characterised by the 

 presence of uniformly binucleate cells, whether these be ordi- 

 nary hyphal cells or spores. Further that during the matura- 

 tion of the teleutospores the twc nuclei at first present fuse to 

 a single nucleus, and that the promycelium, sporidia, and young 

 aecidial mycelium retain this uninucleate character in all the cells. 



Black man shews that when the aecidial fructification is 

 being formed, the up-growing hyphae first cut off a sterile cell 

 at the apex, and the cell immediately beneath this then swells 

 up. At first it, like the rest of the mycelial elements, only 

 ccntains a single nucleus, but it subsequently comes to possess 

 two. The second one is due to the migration of the 

 nucleus from an adjacent cell. Thus there is a process 

 very closely resembling, if not identical with, true fertilisation. 



Botan. Centralbl. Bd. XCVI. 1904 27 



