161 



J^ct", (loc. cit. p. 151). „".7tth the help of these data 



(179) on the polarity of cells, Maula has tried to explain 

 those hailed formations whioh occur so ahxmdantly in 

 wgund V;ood without any previous grafting. Although 

 Maule's attempt at explanation does not seem to me ex- 

 actly convincing nor tenable without many auxiliary hy- 

 potheses, I will nowlet him spook for himself ,- 



Maula starts with the supposition thrt lii new forma- 

 tions of different kinds^- even In wound wood,- the devel- 

 opment of the separate elements is unequal, since seme ate 

 formed early, others are Retarded in development, PihreS, 

 pushing forward, will not he able to maintain their strug- 

 gle to stretch downwards since the callus of the girdling 

 wound hero concerned is closed on the under 9ide, The ' 

 fibres will therefore have to bend. According to B/jSule. 

 the fact, thr.t most fibres are bent tangentially along the 

 tipper surface of the body of the woxind and not radially, 

 may be explained on similar grounds (resistance of the 

 wood). Accordingly, the rootpole of fibre in the adjacent 

 .diagr«an (fig. 71) at first grows out approximr.tely hori- 

 zontally. "If the resistance also becomes too powerful in 

 this direction there results a further bending downward, 

 If possible; if not, then upward. Thereby its rootpole 

 Wl pushes directly on the rootpole of W2 of another fibre, 

 which may possibly have been somewhat retarded In growth, 

 AS a result of this direct contact of two homologous 

 poles. Wg Is obliged to deviate, either towarda.'.the out- 

 side (left) (as in the figuire) or towards the inside 

 (right). There Wz is pushed along on fibre 1, until any 

 further extension is impossible, or the growth in length 

 Q f this fibre 2 is ended. The next fiteo 3 then pushes 

 on W2 with its rootpole Wg aKd must also bend, carrying 

 its rootpole end along fibre 2. — It is evident that the 

 fibres 6, 8. etc., which at last are entirely inclosed, 

 have only a very small space for their extairsion and that 

 finally, necessitated thereto by the pressure of s^xrround- 

 ing fibres, two homologous poles can come exactly together. 

 This, however, does not in any way contradict the polarity 

 of the cells. It is only that the power here forcing the 

 ends apart is less strong than the external pressure, 

 even hoftologous poles of two rod magnets can be brought 

 .together,, if the free nobility of the rods is prevented , 



Tracheid-guares on balls resembling in all essential points 

 those balls described above, are to be found not only within 

 the wound wood formed by the natural cambium, or by newly 

 formed carabial layers but also isolated from "t^ese. in the un- 

 differentiated callus tissue. In the luxuriant c-ambiRl callus 

 of poplar cuttings, ball-like tracheid groups are produced here 

 and there, as already described. In these, as in those des- 

 cribed earlier, we find irregular forms. The root too may be 

 able to produce the same forms of wound wood, as are produced 

 on aciilary parts. The same "balls" may be found in the callus 

 of roots as in that of organs above ground, I investigate^ 

 more closely the callus products of Taraxacum roots. In the 

 basal callus rolls of the cuttings, woody cores are Produced 

 composed of long and short tracheal elements. The cells, how- 



(180) ever, are differently arranged and in such a way that in every 

 section one meets here and there with groups of cells, cut 

 lengthwise, and side by side others c\it crosswise or slanting- 

 ly. In the middle lie the strong3.y bent tracheids, such as 

 described above. Round about this woody co^e there lies a 

 ball-like cambial covering, which on the outside produces con- 



