[ 185 1 



No. 21. 



ON THE CHANNELS OF TRANSPORT FROM THE STORAGE ORGANS 

 OF THE SEEDLINGS OF LODOWEA, PIIfENIX, AND VICIA. 



By henry H. DIXON, Sc.D., F.R.S, 

 Professor of Botany in the University of Dublin ; 



AND 



NIGEL G. BALL, M.A., 

 Assistant to the Professor of Botany in the University of Dublin. 



(Plates VII-XI.) 

 (Read Januakt 23. Printed June IS, 1923.) 



Reasons have been given elsewhere (3 and 4) why it is difficult to accept the 

 generally received view that the bast or phloem is the main channel by which 

 organic substances are transmitted from place to place in the higher plants. 

 The suggestion was there put forward that probably the wood may be more 

 properly regarded as this channel, and evidence which favoured this view was 

 adduced. 



The general presence of tracheae in the connecting channels of the organs of 

 mature plants can possibly be explained by the exigencies of water-supply; 

 hence we cannot draw conclusive inference on this point from the development 

 of tracheae in the bundles connecting the assimilating and storage organs of 

 these plants. 



In the case of some seedlings, however, the conditions are different. Here 

 the storage organs are connected with the embryo, which either has an inde- 

 pendent water-supply from the radicle, or is adequately provided for in this 

 respect of imbibition. Hence, on the assiunption that the phloem is responsible for 

 the transport, we might expect that the xylem, being superfluous, would either 

 not be developed at all in these connecting organs, or would be represented by 

 merely vestigial traces. 



It was then with the object of collecting evidence on this point that we have 

 investigated the structure of the organs connecting the stores with the embryo 

 in some seedlings. 



Lodoicea sechellarum. 



The general course of the germination of this palm has been described by 

 several observers. As is well known, the seed is of remarkable size, weighing, 

 according to Sir William Hooker, 20-25 lbs. (6). It is deeply bilobed, and is 

 covered by a hard black shell — the fruit. In germination the embryo emerges 

 from the dei^ression between the lobes. It develops as a cylindrical mass, 1-5- 

 30 cm. in diameter, and, turning upwards for a little, then pushes its cylindrical 



SCIENT. PROC. B.D.S., VOL. XVII, NO. 2L 2 L 



