Band 140. Nr. 9. XL. Jahrgang. I. Bd. Nr. 9 



Botanisches Centralblatt 



Referierendes Organ v^-^^^^^-^t 



der f^'i^ ... > ^»^^ 



*^/.>' •^-*-^ 



/ -^ 



Association Internationale des Botakis^t^fi» a^*^"^ 

 für das Gesamtgebiet der Botanik. v^V ^* 



Herausgegeben unter der Leitung \^'^'//"*''5llih.55^ 



des Präsidenten: des Vice- Präsidenten: des SecrehlMc^: 



Dr. D. H. Scott. Prof. Dr. Wm. Trelease. Dr. J^ P. Lotsy. 



und der Redactions-Comntissions- Mitglieder : 4 * ' >-~ 

 Prof. Dr. Wm. Trelease, Dr. C. Bonaventura, A. D. Gotton, 

 Prof. Dr. C. Wehmer und Mag. C. Christensen. 

 von zahlreichen Speciah'edacteuren in den verschiedenen Ländern. 



Dr. J. P. Lotsy, Chefredacteur. 



No. 9. 



Abonnement für das halbe Jahr 25 Mark 

 durch alle Buchhandlungen und Postanstalten. 



1919. 



Alle für die Redaction bestimmten Sendungen sind zu richten an: 

 Redaction des Botanischen Centralbiattes, Haarlem (Holland), Spaarneiy. 



Cosens, A. and T. A. Sinclair. Aeriferous tissues in Wil- 

 low galls. (Bot. Gazette. LXIL p. 210—225. 5 Fig. PI. 2— 4. 1916.) 



Two theories present themselves in explanation of the unex- 

 pected appearance of aeriferous tissue in certain regions of insect 

 galls where it is normalh'- absent. The tissue may be regarded as 

 a direct effect of the action of certain environmental factors on the 

 protoplasm of the host; or it may be considered a hereditary 

 tissue that has been reinstated owing to the awakening of latent 

 characteristics in the protoplasm of the infected plant, on account 

 of unusual conditions associated with the presence of the gall- 

 producer. 



The direct evidence from experiments leads us to believe that 

 environmental factors are not directly operative in the production 

 of aeriferous tissue. The anatomical structure of the normal stems 

 of the Salicales furnishes facts apparentlj'^ explainable only on the 

 supposition that we are here dealing with a true heritable tissue. 



The reinstatement in a gall of vestigial characteristics of the 

 plant has an important bearing on the question of gall formation. 

 The producer has long been recognized as exercising a directive 

 control over the activities of the protoplasm of the host, but these 

 examples of the rehabilition of dormant characters show that the 

 forces operating in gall formation are of wider scope. Under these 

 conditions unexpected structures and unusual combinations may 

 well be produced, and in the Interpretation of the morphology of 

 any gall it becomes necessary to discriminate carefully between 

 these two classes of organs and tissues, that is, between those that 

 are simply environmental modifications of the normal and those 



Boten. Centralblatt. Baal 140. 1919 9 



