The Transportation of Pangens 205 



shoot, or the primordium of a transformed leaf becomes 

 a normal leaf, we may assume that other pangens have 

 been given up by the nucleus, than would have been the 

 case without artificial interference. Therefore, in that 

 youthful state, the normal delivery cannot yet have come 

 to an end. When grown cells are stimulated to form 

 callus or wound-cork or, as in Begonia, to produce de 

 novo entire plantlets, it is to be supposed that the pangens 

 that thereby become active must first be aroused from 

 their latent state. 



The transportation of pangens, and their conveyance 

 to the proper places, demands quite special arrangements, 

 the existence of which many a reader will hardly venture 

 to suspect. But who would have dared, ten years ago, to 

 assume the remarkably complicated structure of the nu- 

 cleus ? We must be as sparing as possible with our hypoth- 

 eses, but on the other hand we must not be blind to the 

 fact that since Mohl's time, the investigation of the 

 structure of the protoplast has disclosed more and more 

 differentiations, and that, most likely, we are still far 

 from the end. 



To my mind the currents in the protoplasm form one 

 arrangement for the purpose of this transmission. Every- 

 body knows how they take place in youthful cells at paths 

 that radiate from the nucleus, and more recent investiga- 

 tions have taught how they frequently connect the places 

 of greatest activity directly with the nucleus. 



A few years ago the conviction that these little cur- 

 rents are a quite common peculiarity of plant-cells, was 

 far from being prevalent. The phenomenon was imagined 

 to be limited to a number of instances. Hanstein has 

 already pointed out how little this view was justified, 7 and 

 Velten has proven the presence of currents in all plants 



7 Hanstein, Das Protoplasma, p. 155. 1880. 



