Academy of Sciences in Paris. 363 



fold formed on the root is prolonged to the branches. 9. By 

 this continuation from top to bottom, and from bottom to top, the 

 folds determine the prolongation of the cellular tissue, whence after- 

 wards result the vessels. 10. The evolution of a bud takes place 

 in the same manner as that of a bulbous root, conformably to the 

 order in which the leaves composing it are set on or jointed ; the 

 lowest leaves of the flower were the outermost in the bud, and the 

 highest the most central. If, then, the stem of an exogenous annual 

 be in imagination traced back to the plate or species of cone, which 

 would be represented by that of the root, the innermost layers 

 would answer to the highest verticilli, and the most superficial 

 beds to the lowest verticilli. Although this proposition is not in 

 accordance with the observation of former authors, the reporters 

 consider it as highly interesting, and worthy of being carefully exa- 

 mined by physiologists. 11. The word verticillus must not be 

 wholly considered in the sense in which it has been hitherto used by 

 botanists ; every association of lateral productions of the same 

 nature may be considered as a verticillus, when those productions, 

 if arranged in imagination in a single plane perpendicular to the 

 axis of the stem would move round it without meeting. 12. If the 

 number of branches of the stem of an annual, not taking into ac- 

 count the small upper branches, be divided by the number of 

 the verticilli) the quotient will be the number of layers of the lower 

 part of the stem. This interesting observation has been verified 

 by the reporters upon several pieces of atriplex patula. 13. The 

 only difference between an annual and a perennial plant is in the dura- 

 tion. The evolution of each bud takes place in the second year, in the 

 same manner as that of the embryo took place in the preceding year. 

 In the branches, as in the stem, the outermost beds correspond with the 

 lowest verticilli, and the innermost with the highest. On the other 

 hand, the innermost beds of the branch correspond with the most 

 central zones of the stem, and the outer beds of the former with the 

 superficial zones of the latter. 14. The outer edge of the sap 

 (qubier) is always the same ; the increase in size of each bed 

 takes place in the interior by the intercalation of new fibres. 

 Thus the development of the exogenous, or dicotyledon, is in each 

 bed really analogous to that of the endogenous or monocotyledon. 

 15. The inner beds press the exterior ones outwards; the fibres 

 of the inner beds become intercalated with those of the outer 

 ones; and thus the plant augments in circumference. 16. In the 

 bark, the most recent fibrous bundles have a tendency to inter- 

 mingle also with those of anterior formation ; they push them 

 outwards and pass beyond them, on the side turned towards the 

 centre ; whence it follows that the inner surface of the bark is 

 incessantly changing. 17. The increase in size does not result 

 from the addition of a new body to a body already in existence, but 

 from a centrifugal evolution of the latter ; this evolution is operated 

 upwards, along the length of the stem, by the influence of the roots ; 



