400 



VASCULAR CR VP TOGA MS. 



The Branching of the Equisetaceae depends exclusively on the formation of 

 lateral buds. Each of these is formed from a superficial cell lying just above the 

 youngest foliar girdle, and this takes place at points alternating with the sheath-teeth, 

 long before the differentiation of the fibro-vascular bundles. [It was thought 

 that these buds were of endogenous origin \ but the researches of Janczewski and 

 of Famintzin have shown that this is not the case^] Hofmeister was the first to 

 show that each bud proceeds from a single cell of the tissue ; and although I have 

 myself never seen it in a unicellular condition, I have found rudimentary branches 

 composed of only two or four cells; and these showed that even the first three 

 divisions of the mother-cell of the branch are inclined in three directions in such 



Fig. 282. — External view of three teeth of a young 

 leaf-sheath of Equisetwni Telntateia. 



Fig. 281.— The same as Fig. 280, but at a. greater distance from the apex, showing a further advance of the differentiation of 

 leaf-sheath and internode ; r r cortex of the upper, r' ■/ r' cortex of the lower internode, e e the inner, e' e' the outer epidermis 

 of the leaf-sheath, ^^ the foliar portion of the fibro-vascular bundle,^' ^'^ its descending portion belonging to the internode ; 

 the first annular vessel is formed at their point of meeting. 



a manner that a trilaterally pyramidal apical cell is produced; and the first three 

 divisions thus form the first three segments. Lateral buds of the rhizome of 

 E. Telmateia and E. arvense, late in the autumn or early in the spring, usually 

 show in longitudinal section all the stages of development of. the buds. After 

 they have formed several foliar girdles and their apex is covered by a firm envelope 

 of leaf-sheaths, they break through the base of the parent leaf-sheaths. They 

 may also remain dormant for a long period, as is shown by the circumstance 

 that buds break out when the underground nodes of ascending stems are exposed 



^ See also the account of the Jungermanniese, p. 359. 



^ [Janczewski. Rech. sur le dev. des bourgeons dans les Preles ; Mem, Soc. de Sci. Nat. de Cher- 

 bourg, XX. 1876-77.— Famintzin, Bull, de I'Acad. Imp. d. St. Petersbourg, XXII. 1876.] 



