THE HIGHER CRYPTOGAMIA. 205 



no Coleorhizse are usually visible here, is, that (as in the 

 case of axile superficial adventitious-root-formation) the 

 direction of the root-branch in its earliest stage, generally 

 follows the axis of the root. The bark of the latter is 

 pierced by the former during the young state of the cells 

 before they have attained their final thickness. The con- 

 tinual amalgamation of the contiguous cells of the root 

 and its branch obliterates all traces of the gradual perfo- 

 ration. 



During the first divisions of the rudimentary cells of the 

 stem, frond, and root, the two others of the four primary 

 cells of the embryo multiply by the formation of oblique 

 longitudinal and transverse septa (PI. XXVIII, fig. 3 ; 

 PI, XXVI, fig. 6), so that the embryo assumes altogether a 

 spherical form. Only the rudiment of the first frond ap- 

 pears at an early period as an elongated point. 



Prom the time when the outer limits of the rudimen- 

 tary cell of the root are fixed by the formation of the 

 first cell of the root-cap, the cells of the upper surface 

 of the primary axis, and also the neighbouring cells of 

 the growing root, enter into close combination with the 

 adjoining cells of the prothallium.* The result is a 

 complete amalgamation of the adjoining outer surfaces 

 of the cells, which cannot now be detached from one 

 another by mere mechanical means. Henceforth the 

 embryo which up to this point lay free in the cavity 

 of the enlarged central cell of the archegonium, ad- 

 heres firmly to the prothallium. The adjoining cells 

 of each remain tolerably even. The attachment of the 

 embryo is not the result of arrangements such as we 

 find in the analogous process of the ingrafting of the 

 fruit of a moss into the axis of the mother-plant ; nor is 

 there any elongation of the basal cell of the fruit rudi- 

 ment into a capillary tube, becoming curved where it 

 penetrates the stem, as is the case in many Jungermanniac ; 

 nor is there as in Anthoceros any development of pro- 

 cesses from the cells of the broad, slightly convex, under 

 surface of the young fruit. From the moment of the 

 commencement of the amalgamation, the cells of the 



* Sec Mohl in 'Wagner's Handworterbuch dcr riiysiol.,' vol. iv, p. 279. 



