65 



But BEIJERINCK is not blind to the fact that still other factors 

 play a part. "Ein unbekannter Einfluss, welcher von den Seiten- 

 knospen ausgeht" is certainly one of them. He even came to the con- 

 clusion that "zwischen Wurzel- und Knospenbildung eine, gegenseitig 

 forderende Correlation existirt". Especially in the light of modern 

 conceptions on the formation of "auxins", such statements are cer- 

 tainly remarkable. 



BEIJERINCK has endeavoured also, by an anatomical study, to 

 indicate the points in the tissues where the adventitious formations 

 first become visible. In every specific case studied by him, he has 

 ascertained whether this formation is effected on callus or "normally", 

 and in the latter case whether they must be called endogenous or exo- 

 genous. For the endogenous formations he has completely confirmed 

 the significance which VAN TIEGHEM i) and his pupil MOROT 2 ) 

 attributed to the pericycle (BEIJERINCK, whose treatise was ready 

 before the appearance of MOROT'S speaks usually of the pericambium, 

 where the term pericycle should be preferred). 



BEIJERINCK'S studies enabled him to draw up rules for the relation 

 between the location of the lateral roots, and thus also of the root 

 buds, and the structure of the vascular bundle in the roots. These 

 rules were corrected in 1888 by VAN TIEGHEM and DOULIOT 3 ) in a 

 few minor points only. 



One main result of these anatomical observations, namely, that 

 specialized cells are suitable to serve as a starting point for ad- 

 ve-^itious growth, leads BEIJERINCK back to the consideration of 

 ontogenesis. He formulates the opinion that "jede lebende Zelle die 

 ganze Pflanze neu erzeugen kann", and introduces as a remarkable 

 auxiliary hypothesis that "die Reproductionsmoglichkeit auf der 

 Gegenwart des Zellkernes, die Reproductionsleichtigkeit auf der 

 Beschaffenheit des Cytoplasmas beruhen". He assumes that the nu- 

 clei lose something during growth and division, and that this loss 

 halts the divisions, but that whatever is lost may be restored by a 

 vigorous supply of nourishment, among other things. Such a supply 

 would present itself by changes in direction of the transport streams 

 in the plant tissue; thereupon renewed divisions, that is to say, ad- 

 ventitious formations, should occur. One observes here not only how 

 strongly BEIJERINCK was influenced in those days by DARWIN'S 

 theory of pangenesis, but also that he applied it in a very original 

 manner. 



Of interest are BEIJERINCK'S general remarks on observing that 

 many root-buds may be considered to be metamorphosed root- 

 beginnings, while he considers the opposite transformation, viz., buds 



') PH. VAN TIEGHEM, Traite de botanique, Paris 1884. 



2 ) L. MOROT, Recherches sur le pericycle, Ann. sciences nat. Bot., 6e ser. 20, 

 217-309, 1885. 



3 ) PH. VAN TIEGHEM et H. DOULIOT, Recherches comparatives sur 1'origine des 

 membres endogenes, Ann. sciences nat. Bot., 7e ser. 8, 1 660, 1888. 



M. W. Beijerinck, His life and his work. 5 



