THE STEM OR SHOOT. 



133 



to that found in Ly cop odium Selago during the develop- 

 ment of the bulbils on the stem, in which a basal leaf 

 is formed before any other organ makes its appearance; 

 yet in both these cases the precocious foliar organ must 

 be regarded as being attached to as yet undifferentiated 

 tissue of the axis of the bud ; in B. manicata this never 

 develops further and becomes merged in the tissue of 

 the leaf -vein. Transitional stages between these epi- 

 phyllar emergences of Begonia and foliage-leaves have 

 been observed, a fact supporting the view expressed 

 above. 



In this connection mast be mentioned a most inter- 

 esting account by Dr. Marie Stopes of the normal 

 mode of origin of the lateral branches of Cycas revoluta, 

 as observed by her in Japan. The "buds," which may 

 develop into quite large, thick lateral branches, " may 

 arise, apparently, at any time," but the interest of the 

 phenomenon lies in the fact that they originate, not in 

 the axils, but on the upper surface of the scale-leaves of 

 the stem, a short distance away from the axil. At first 

 there is no connection between their vascular system 

 and that of the stem, and in a young stage they may 

 produce one or two adventitious roots. At a later 

 period, however (as, of course, must necessarily be the 

 case), when the buds become well-developed branches, 

 complete vascular connection with the main stem is 

 established. 



Now the Cycads are a group intermediate between 

 the Ferns and the Angiosperms; in the former of these 

 two lateral shoots are produced, in the majority, in an 

 extra-axillary position on the stem, or, in other cases, 

 on the petiole, and it is exceptional to find them, 

 as in the Hymenophyllaceas, in an axillary position ; in 

 the Angiosperms they are always axillary. The mode 

 of forming lateral shoots in Cycads would seem to 

 be transitional between that of the other two groups, 

 viz., always adventitious on the petiole a short way 

 from the axil. In view of what has already been 

 stated (see p. 126) with regard to the real position of 



