Band 108. Nr. 10. XXIX. Jahrgang. IL Bd. Nr. 10. 



Botanisclies CentraMatt. 



Referirendes Organ 



der 



Association Internationale des Botanistes 

 für das Gesamtgebiet der Botanik. 



Herausgegeben unter der Leitung 



des Präsidenten: des Vice- Präsidenten : des Secretärs: 



Prof. Dr. R. v. Wettstein, Prof. Dr. Ch. Flahault. Dr. J. P. Lotsy. 



und der Redactions-Commissions- Mitglieder : 



Prof. Dr. Wm. Trelease, Dr. R. Pampanini und Prof. Dr. F. W. Oliver. 



von zahlreichen Specialredacteuren in den verschiedenen Ländern. 



Dr. J. P. LOTSY, Chefredacteur. 



Nr. 36. 



Abonnement für dass halbe Jahr 14 Mark 



durch alle Buchhandlungen und Postanstalten. 



1908. 



Alle für die Redaction bestimmten Sendungen sind zu richten an Herrn 

 Dr. J. P. LOTSY, Chefredacteur, Leiden (Holland), Witte Singel 26. 



Art. 6. des Statuts de 1' Association intern, d. Botanistes: 

 Chaque raembre prend l'engagenient d'envoyer au redacteur en 

 chef et aussitot apres leur publication un exemplaire de ses travaux 

 ou ä defaut leur titre aceompagne de toutes les indications bibliogra- 

 phiques necessaires. 



Le-wis, C. E., The embryology and development of Riccia 

 lutescens and Riccia crystallina. (Bot. Gaz. XLI. p. 109 — 139. pls. 

 5—9. March 1906.) 



From extensive field studies and greenhouse cultures the con- 

 clusion is reached that Riccia lutescens and Ricciocarpus natans are 

 forms of the same plant, the former replacing the latter as the 

 season advances and the water of a pond dries up. The ground form 

 is not sterile, as has been claimed by other writers, but the sexual 

 Organs appear in autumn while the thalli are growing on the ground , 

 and mature the foUowing spring even when supplied with only a 

 moderate amount of water. The sexual organs and fruit are found 

 to resemble those of species previously studied. Centrosomes are not 

 found outside the antheridium; in this organ are found bodies resem- 

 bling centrosomes, which arise de novo with each cell division, 

 but after the last division of antheridial cells remain in the sper- 

 matids and later become blepharoplasts. Two sperms are formed in 

 each cuboidal cell of the antheridium. The chromosome numbers 

 are four for the gametophyte and eight for the sporoph5'^te. 



M. A. Chrysler. 



l^ichols, M. L., The Development of the Pollen of Sarracenia. 

 (Bot. Gazette. XLV. 1908. p. 31—37. Plate 5.) 



This study of reduction phenomena in the pollen mother cells 

 Botan. Centralblatt. Band 108. 1908. 16 



