autumn transplanting was attended with much greater danger for the twisted 

 specimens. To aid in the removal, the plants were pulled slightly and, in 

 doing so, it became evident that the twisted specimens broke very easily at 

 the first bend in the root. 



It is, therefore, advisable to cut the seedling tap roots at once at the first 

 transplanting, so that several root branches are formed at the root neck; 

 those near the cut surface develop new lateral axes in the second year. 



This makes possible not only an increase of the organs of absorption but 

 also causes the production of a root ball in which the earth is held between 

 the numerous roots. 



PrantF first studied thoroughly the anatomical changes which occur 

 when younger roots, especially the germinating ones, are injured. He found 

 in vegetables (peas, horse beans, etc.) that the loss of the tender root tip 

 was completely made good by the development of a new one in which all the 

 tissue systems participated if the injury took place close to the tip of the 

 root. If he cut off the germinating root somewhat further back from the 

 apical cell regeneration took place but all the tissues did not participate in 

 this, only the juvenile vascular strands. The method of cutting, used almost 

 exclusively in general practice, viz: the one injuring the mature tissues, 

 does not bring about a regeneration of the root tip ; instead of this, callus 

 formation by the bark body sets in, thereby covering the cut surface. 



Nemec's" work is even more thorough and comprehensive. 



In contrast to the assunTption that true regenerations, in w^hich the part 

 removed from the individual is directly formed anew in its original shape 

 and with its original physiological peculiarities, rarely occur in the vegetable 

 kingdom, experiments show just the opposite for roots. 



It is here only a question of injurying the youngest possible organs. In 

 roots, restitution remains limited really to the zone where the cells on the 

 whole wound surface (possibly with the exception of the epidermis and the 

 outermost bark layers) are still meristematic. As soon as the cells of the 

 outermost bark layers, together with the central rows of the sclerome, 

 approach maturity, the meristematic cell layers alone, adjoining the pcri- 

 cambium, participate in the regeneration. It is found further that the vege- 

 tative point of a root, of which the meristematic cells externally appear uni- 

 form, still possesses a certain specialization. The cells are not equipotential 

 and can not produce different tissues under arbitrarily changed conditions. 

 Such specific differences are present in the "Statocytes." The mobility of 

 starch grains in these presupposes specific peculiarities of the protoplasm, 

 since in different callus-like hypertrophied cells starch grains are also formed 

 which at times can be still greater than those of the statocytes and yet, under 

 the influence of gravity, cannot be moved easily. The fact that, under the 

 influence of a sufficiently strong centrifugal force, they can move cen- 



1 Prantl, Untersuchunfren iiber die Regeneration des Veg-etations-punktes an 

 ang-iospermen Wurzeln. Wurzburg 1S73. 



2 Nemec, B., Studien iiber die Regeneration. Berlin 1905, Gebr. Borntrager. 



