Band 122. Nr. 6. XXXlV.Jahrgang. I. Bd. Nr. 6. 



Botanisches Centralblatt. 



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. E. Warming. Prof. Dr. F. W. Oliver. Dr. J. P. Lotey. 



und der Redactions-Commissions- Mitglieder : 



Prof. Dr. Wm. Treleass, Dr. C. Bonaventura, A. D. Cotton, 



Prof. Dr. C. Wehmer und Dr. C. H. Ostenfeld. 



von zahlreichen Specialredacteuren in den verschiedenen Ländern. 



Dr. J. P. Lotsy, Chefredacteur. 



No. 6. 



Abonnement für das halbe Jahr 14 Mark 

 durch alle Buchhandlungen und Postanstalten. 



1913. 



Alle für die Redaction bestimmten Sendungen sind zu richten an: 

 Redaction des Botanischen Centralbjlattes, Haarlem (Holland), Spaarne 17. 



Gordon, M., Ray Tracheids in Sequoia sempervirens. (New 

 Phytologist. XI. W 1. p. 1—7. Text-figures. 1 — 7. Jan. 1912.) 



The author gives a short historical summary of the investi- 

 gations on the medullary rays of the genus Sequoia, and describes 

 the occurrence of both marginal and interspersed ra)^ tracheids, 

 in old stem wood of 5. sempervirens. 



The marginal ray tracheids are elongated, have an irregulär 

 margin, differ in shape from the parenchyma cells of the ray and 

 are scattered on both sides of it. The author considers that they 

 recall some of the structures found in Pinus by Thompson, and 

 considered b}^ him to be of a primitive type. 



The interspersed ray tracheids are similarly situated, but are 

 regulär in outline closely resembling the ordinary ray cells in 

 form, though differing in the pitting. The pitting forms a "ready 

 and absolutely reliable basis" serving to distinguish the two con- 

 stituents of the ray. 



The replacement of ray tracheids by parenchyma is a very 

 indefinite process as compared with the pines, and indications of 

 transitional Clements are more obvious, for simple and bordered 

 pits occur on the same dement. 



No true ra}' tracheids were found in the fossil forms of Sequoia 

 examined, but it is suggested that the marginal cells of 5. P^>?Ä«//ow/y 

 may be derivatives of ray tracheids. E. de Fraine. 



Ironside, A. F. The Anatom ical Structure of the New 



Botan. Centralblatt. Band 122. 19K;. 



