276 HOFMEISTER, ON 



leaf (often of the third or fourth-youngest leaf), and in 

 the second or third layer beneath the surface of the latter, 

 becomes distinguishable from the neighbouring cells (which 

 often already contain chlorophyll), by its increase in size, 

 and still more by its colourless thickly mucilaginous 

 contents. This cell often lags behind its neighbours in 

 longitudinal growth, in consequence of which its connexion 

 with the cells above it and at its sides is dissolved. Division 

 soon commences in it, and is repeated in different directions 

 in rapid succession in the terminal cell. (PL XXXV, figs. 1 1 , 

 12). Thus a cell-multiplication is set on foot which corre- 

 sponds in all respects with the preceding multiplication of 

 the apical cell of the terminal bud. The presence of the 

 adventitious bud is soon indicated by a protrusion of the 

 outer surface of the stem close under the place of insertion 

 of the leaf. Ultimately by further longitudinal growth 

 it breaks forth from the under-side of the sheath-like 

 leaf. 



The adventitious buds of Equisetum have the peculiarity 

 of being able, under certain circumstances, to remain long 

 dormant, a peculiarity which they possess in common with 

 the adventitious buds which arc produced in mosses and 

 phrenoganis upon the outer surface of the young stem 

 in the axils of leaves. They often pass the greater portion 

 of a period of vegetation in the most rudimentary condi- 

 tion, consisting of one or at most of a few cells. This is 

 the case with the adventitious buds of E. pratense, palustre, 

 and limosum, which are destined to reproduce the species. 

 Although in spring numerous thin branches break out from 

 the base of the leaf-sheath of the middle and upper part 

 of the above-gronnd shoots, the number of which branches 

 is usually the same as that of the leaf-tips, yet the adven- 

 titious buds of the lowest internodes those which are 

 buried in the earth remain entirely dormant until late 

 in autumn. At that time, however, one only of the buds 

 of each of those internodes developes itself but with a 

 strength and activity which far exceeds that of the subter- 

 ranean branchlets. 



Individual internodes of the lower subterranean portion 

 of the main shoots of Eq. arvense become swollen, whilst 



