53 



the development and the morphological structure of these galls, on the 

 j.natomical structure and on the adaptation to external influences. 

 This is all illustrated with not less than 1 00 original illustrations, most 

 of which are classical examples as to how scientific exactness may be 

 combined with clear arrangement and artistic taste. It is not sur- 

 prising that several of these drawings have been copied in the most 

 important surveys and textbooks dealing with plant-galls. 



We should mention here that in the reproduction of the plates for 

 Beijerinck's Verzamelde Geschriften these drawings, which appeared 

 originally as lithographs, have suffered severely; cecidologists are 

 advised, therefore, to consult the plates in the original. 



These drawings cost Beijerinck a great deal of effort ; twenty- 

 five years later he still spoke of the fatigue he feit afterwards. It is 

 further of importance that it was Beijerinck's wish to add to these 

 uncoloured drawings half-a-dozen coloured ones, for which his 

 sister drew large plates after Beijerinck's sketches. These coloured 

 plates are especially attractive »). Presumably, the question of cost 

 has prevented the Academy from reproducing them. It was a great 

 disappointment to Beijerinck that they were not printed, and he 

 even suggested in 1921 that they be inserted in his Verzamelde Ge- 

 schriften. 



Much of what is mentioned in the important treatise is now well 

 known to cecidologists, but the latter are commonly not aware of how 

 much they owe to Beijerinck. 



It is impossible to give here an adequate outline of the contents. 

 However, we think it well to mention that after a general chapter on 

 the "Cynipiden und ihre Gallen" (Beijerinck states that in the five 

 years before the appearance of his publication approximately 50 

 different Cynipidae-ga.\ls were investigated in the fresh condition), a 

 restricted number of galls and their inhabitants were subjected to a 

 closer discussion. These elaborate discussions refer to a. the Hiera- 

 cium-gall, b. the Terminalis-gall and the Aptera-gall, produced by the 

 same wasp, c. the Baccarum-gall and its Folium-gall, d. the Mega- 

 ptera-gallanditsRenum-gall, e. the Kollari-gall, inhabited by Cynips 

 Kollari, an insect of which Beijerinck still assumed in 1882 that it 

 reproduced itself exclusively parthenogenetically, and that new Kol- 

 lari-galls developed under the influence of its eggs, and ƒ. the Ortho- 

 spinae-gall. 



Xertainly no one who wishes to become thoroughly acquainted 

 with these important galls can ignore Beijerinck's work, though his 

 observations require alteration or completion in some points. 



We shall specify further only a few of the more important ob- 

 servations made by Beijerinck. In the first place it must be recalled 

 that he succeeded in fixing several gall-wasps in the act of ovulation, 



1) They are kept in the Laboratory for Technical Botany of the University College 

 of Technology at Delft. ' 



