762 



ill this case oiilv a very slight influence of the ringing upon the 

 root-growth. 



This evidently does not fir in witli Dixon's view; if the transport 

 is effected along the periphera,! parts of tlie xyleni, ringing must in 

 these plants have the same effect. It struck me, therefore, that if 

 would be worth while to. repeat some of Hanstein's experiments. 

 The Solanacea C'eslnim auraiitiacnm proved to be an unsuitable 

 subject since detached branches sent out roots very sparingly in 

 water culture, liiit Neriiim Oleander yielded quite satisfactory results: 

 all the twelve cuttings presented an aspect, quite in harmony with 

 Hanstein'8 description. Tlie root-growth may be somewhat more 

 abundant above the wound, but the behaviour is quite different 

 IVom e. g. that with Salix and Cornus spec. In these the roots 

 appear almost exclusively above the wound, unless the stem-piece 

 below it be very long, and the once formed roots are even destroyed 

 when the bark above them is stripfied off. 



Provisionally all this tells very strongly against the validitj' of 

 Dixon's conception of a transport of the carbohydrates and the 

 |)rotein8 along the pei'ipheral xylem. 



if the above-discussed experiments with variegated shoots could 

 also be made with variegated Oleamleis, the medullary phloem of 

 these plants would probably cau,se a quite different result from 

 that yielded by Aesculus and Acer. But unfortunately variegated 

 Oleatiders I had imt at my disposal, so that now 1 made a trial 

 with ringed, normal shoots, which, while still attached to the plant, 

 were wrapped up in black paper. The re.sulf was rather conclusive. 

 Although some leaves had fallen off, the shoots themselves were 

 still alive ten weeks after the ringing and had iiicieased in length. 



We see, therefore, that not only in the formation of the roots of 

 branches in water-culture but also in the budding and the growth 

 of Oleander Aesculus and Acer Negundo in spring, the results of our 

 experiments with I'inged branches imply a transport along the piiloem. 



In a subsequent publication 1 intend to discuss the question 

 whether the capacity of these paths is sufficiënt. 



For the present the above observations on Aesculus and Acer Negundo, 

 where the detached branches did not bleed, are not applicable to the 

 cases in which this bleeding is so copious, and as with Betiila alba 

 the highly saccliariferous .sap is exuding directly after the liuging '). 



') The cases described by Molisch, (Bot. Zig. 19U2) as wounil-reaclion with 

 local bleeding pressure, are of quite a different nature; then the bleeding pressure 

 manifests itself only after days or weeks. 



