M even's Report for 1839 on Physiological Botany. 253 



and also by new observations, and I have often declared that 

 no one has ever seen the tearing of the spiral fibres ; but that 

 the reticular spiral tubes are produced from developed annu- 

 lar tubes, I think I may positively assert ; Imp aliens Balsa- 

 mina, and the flower-stalk of Musa, showed me this very 

 plainly. 



In the cells of the outer layer of the capsule of Hepatica, 

 where rings only are almost always found, and interrupted, 

 inasmuch as they do not extend over the outer wall of the 

 cells, one can see that they are really original, and are not pro- 

 duced by the resorption of isolated ends of the spiral fibres *. 



M. Decaisnef has laid before the Academy at Paris a trea- 

 tise on the structure of the beetroot, on which M. Brongniart 

 has given a report. M. Decaisne observed the development 

 of the beet from the germination of the seed up to its perfect 

 state ; he saw that the beet consisted as rt were of two parts 

 of distinct origin ; the upper part formed out of the enlarged 

 stipes, the lower out of the rootlets of the embryo. The se- 

 paration of both parts may be seen in sections of the root by 

 means of the pith, which is continued in the form of a cone as 

 far as the commencement of the root, but is wanting in the 

 true root. Round about the pith are true spiral tubes, but 

 in the true root there are only reticular tubes. 



The vascular bundles stand in regular circles, and their 

 number increases toward the exterior ; outwardly they are sur- 

 rounded by fine elongated cells which represent the woody 

 tissue of plants. In the beet there are three different tissues : 

 1. Parenchyma, which is colourless in the common beet, but 

 in others is filled with a red or yellow sap. 2. The reticular 

 spiral tubes. 3. Elongated cellular tissue, which is very fine 

 and transparent, and accompanies the spiral tubes, but is ge- 

 nerally deposited towards the exterior. 



This tissue represents, by the position it occupies as well as 

 by the lacteous vessels it contains, both the ligneous tissue and 

 the bast of the bark. That the parenchyma of the beet con- 

 tains little or no sugar is well known ; it may be distinguished 

 by the taste alone, that the cellulo-vascular parts of the beet 

 are sweeter than the others. M. Raspail's hypothesis, that 

 the sugar is found in the spiral tubes, is, as might be expected, 

 completely disproved by M. Decaisne's researches, and he con- 

 cludes that the sugar is formed principally in the fine tissue 

 which surrounds the spiral tubes. The upper part of the root 



* Vide Muller's Archiv, 1839, tab. xiii. fig. 47. 



t Rapport fait a l'Academie par M. Ad. Brongniart, Janv. 14, 1839. — 

 Annates des Sciences Nat., xi. p. 49. 



