266 HOPMEISTER, ON THE HIGHER CRYPTOGAMIA. 



The arrangement of the fronds in both was antidromal, 

 and in one of them always passed by degrees into that of 

 the older undivided axis, whilst the frond-arrangement of 

 the adventitious shoots of Aspidium jilix-mas is usually 

 homodromous with that of the principal stem, and rarely 

 antidromous to it. 



With regard to Pteris aquilina the inadmissibility of the 

 views of Karsten and Mettenius is still more manifest. I 

 have seen stems of Pteris aquilina with naked frondless 

 unbranched ends of considerable length, whose youngest 

 branch disclosed no rudiment of a frond. This was the 

 case (amongst many other instances) throughout a length 

 of eight inches in a portion of the end of a stem, and 

 throughout a length of 2^ inches in the youngest branch. 

 This is proof of undoubted bifurcation. The supposition of 

 Mettenius would also require that (when the first frond of 

 the sub-axis is inserted on the side turned towards the 

 principal axis) a bud inserted on the hinder edge of the 

 stipes should, by its early development, push away the 

 frond from the principal axis to which it belongs. It would 

 follow also that the front surface of its lamina must be 

 turned towards the latter, or in other w r ords its stipes must 

 exhibit a tension of 180°. Neither of these two circum- 

 stances occurs. 



Finally a real difference exists between the internal 

 structure of the forked branches of the stem and that of 

 the place of junction of the principal stem with, the buds 

 which I have considered as adventitious and seated on the 

 stipes. The former exhibit throughout their entire length 

 the peculiar structure of the stem. Their two axile vas- 

 cular bundles, and the sheaths of the latter, are united 

 immediately with the corresponding portions of the tissue 

 of the principal axis. The tissue on the other hand which 

 lies between the principal axis and the place of origin of an 

 adventitious bud, exhibits the characteristic arrangement 

 of the vascular bundles of the stipes. 



