56 • 



temporary. He concluded that the latter is the case. He points out 

 that excessive nutrition of a plant organ altered by gall formation 

 does not result in enlargement of the cecidium, but that formations 

 are produced of the same type as may occur by excessive nutrition on 

 the unaltered organ. As a typical example, he calls special attention 

 here again to the above-discussed change of the "gall-roots" of the 

 Poae-gall into normal roots; as another example he describes the 

 formation of normal roots within the surviving gall caused by Nema- 

 tus viminalis on Salix pur pur ea. 



Parallel to this Beijerinck gives examples from which it appears 

 that the properties of the mother plant are still traceable in the gall. 

 "Die samtlichen Differenzen, durch welche die Blatter von Rosa 

 canina, R. ruhiginosa, R. rugosa und R. acicularis unter sich ver- 

 schieden sind", were recognized in "den Anhangsgebilden der Bede- 

 guare von Rhodites Rosae" , when Beijerinck produced in his garden 

 the Bedeguar Gall (popularly known as "Robin Pincushion" or "Moss 

 Gall") on the Rosé species mentioned with the aid of the gall-wasp. 

 Thus Beijerinck is led to the following conclusion : "Es existieren in 

 dem Protoplasma, welches sich auf dem Wege der Cecidiogenese be- 

 findet, zwei selbstandige Klassen scharf getrennter und grundver- 

 schiedener Eigenschaften, namlich erstens, diej enige der erblichen, 

 dem Cecidium und der Nahrpflanze gemeinsamen, und zweitens, die- 

 j enige der temporaren, nur dem Cecidium eigenthümlichen Charactere. 

 Die letzteren besitzen überhaupt keine Constanz, und vermogen sich 

 keiner einzigen Neubildung, welche von den Geweben des Cecidiums 

 an sich erzeugt werden, aufzupragen". 



In this treatise Beijerinck for the first time announces also the 

 hypothesis on the enzymatic nature of the cecidiogenous substances. 

 He found, namely, that Nematus-gall (unlike the Cynipidae-gaMs) 

 continues its development after the egg therein has been killed. He 

 ascribed the development, in this particular case, to poisonous matter 

 passed along with the egg by the mother insect. After making an 

 estimate of the quantity of this poisonous matter, he concluded that 

 an infinitesimal quantity of it must exert an enormous influence on 

 the growth of many cells. It is this circumstance which he expressed 

 by denoting the substance as a "Wuchsenzym". We shall return to 

 this opinion later on (it was contested by Magnus in 1903 i) and in 

 1914 2)). 



In the writer's opinion the publication on plant-galls containing the 

 largest number of new ideas is the one published in 1896, again as a 

 communication of the Royal Academy of Sciences at Amsterdam ^), 



1) W. Magnus, Zur Atiologie der Gallbildungen, Ber. d. deutsch. bot. Ges. 21, 129- 

 132, 1903. 



2) W. Magnus, Die Entstehung der Pflanzengallen verursacht durch Hymenop- 

 teren, Jena 1914. 



3) Verhandelingen Koninklijke Akademie van Wetenschappen Amsterdam, 2de Sec- 

 tie, 5, 1896 {Verzamelde Geschriften 3, 199-232). 



