STRUCTURE.] SPIRALS TERMINATION. 71 



when coloured fluids rise in spiral vessels, he saw them follow 

 the direction of the spires. This last fact may, however, be 

 explained upon the supposition that they rise in the channels 

 formed by the approximation of cylindrical fibres, and not in 

 the fibres themselves; in which case there could be little 

 doubt that the fibres are really solid; and I must declare 

 that I can find no such appearances as those described by 

 M. de Buzareingues ; any more than I can the shadow of 

 proof of another statement by the same physiologist, viz., 

 that the fibre often runs between two cylindrical tubes, so 

 that there is not only an outer membrane, but an inner one 

 also. He adds that the inner tube contains air, but that fluid 

 is lodged in the space between the two tubes. Such observa- 

 tions cannot be verified, because the learned author on no 

 occasion names the plants in which he has remarked these 

 peculiarities of structure; and as they have hitherto escaped 

 the most skilful vegetable anatomists, they can only be re- 

 garded as singular errors caused by insufficient investigation. 



Link contends, that the fibre, although simple at first, soon 

 forks and forks again, and that the branches thus produced 

 all follow the direction of the spire. 



Schleiden regards the spiral as always originally consisting 

 of two bands, corresponding to an ascending and descending 

 current of organisable matter ; and he believes the extremities 

 of the bands to pass into each other at the end of the cells, 

 and at a very early period, in most cases, to cohere into a 

 single band. I cannot say that I have ever been able to 

 verify this conjecture. 



The termination of spiral vessels is, beyond all doubt, 

 conical. This was stated by Nees Von Esenbeck, in his 

 Handbuch der Botanik, published in 1820; and in 1824 

 Dutrochet asserted, that they end in conical spires, the point 

 of which becomes very acute ; but one would not suppose, 

 judging from the figure given by the latter writer, that he 

 had seen the terminations very clearly. If the point of a 

 spiral vessel in the Hyacinth (Plate II. fig. 9.) be examined, 

 it will be seen that the end of the spiral fibre lies just within 

 the acute point of the vessel, and that the spires become 

 more and more relaxed as they approach the extremity, as if 



