276 Prof. H. Karsten on the Formation, 



their interior than the ligneous cells themselves, and this even 

 without any wounding of the vessels. I removed a ring of bark 

 from a twig of Salix babylonica, and found, in the following 

 year, all the vessels of the peripheral lamina of the wood entirely 

 filled with cells, whilst the woody cells, on the contrary, remained 

 unaltered. The cells thus formed in the interior of vessels 

 may, under certain circumstances, be transformed into new 

 vascular cells, after the thickened wall of the parent vessel has 

 been absorbed, and may contribute to the lengthening of the 

 original vessel — a case which I have described and figured, in 

 my researches on the organs of vegetation of the Palms, with 

 regard to Lycopodium Springii (pp. 120 & 163, pi. 9. fig. 15), 

 the vascular bundle alone having been developed into a root- 

 fibre. 



By the maceration in solution of potash of the cells which 

 make their appearance in the vessels during the formation of 

 callus, it may also be demonstrated that they are not produced 

 by constriction, but as free vesicles in the fluid contents of the 

 cells and vessels, although the observation of the moment of 

 their production presents exactly the same difficulties here as in 

 the case of the suberous tissue. 



§ II. On Cell-formation in (Edogonium. 



New joint-cells by evolution of endogenous cells. — Absorption of the 

 secretions of the mother cell, with contemporary formation in the 

 daughter cells.— Absorption of the nuclear cell. — Development and 

 growth of the nuclear cell. — Cellular contents of the developed joint- 

 cells. — Downward-prolonged annular folds of the primary cell-wall. — 

 Bary's globules of decomposition contain animal parasites. 



The peculiar behaviour of the mother cell, in the several spe- 

 cies of the genus (Edogonium, during the formation of daughter 

 cells, has been most fully elucidated by Bary (Schriften der 

 Senkenberg'schen Gesellschaft, Band i. 1854-55). From his 

 investigations we know that, in the course of elongation of a 

 joint- cell, the primary cell-wall forms at its upper part an in- 

 growing annular fold, and that this fold, after the membranous 

 envelope covering the mother cells is torn through, suddenly 

 extrudes itself, and thus causes a considerable elongation of the 

 joint-cell. 



The internal structure of the (Edogonium-cdh and the mode of 

 multiplication of the joint-cells have, however, not yet been ascer- 

 tained. The latter is, as usual, represented to be a consequence 

 of the formation of septa by constriction of the walls ; and, ac- 

 cording to Bary, the septum is formed in the suddenly extended 

 cell within a colourless layer which divides the green mass of 

 contents into two parts, and not until this layer has issued from 



