180 THE JOURNAL OF BOTANY 
Indeed, botanists generally are not, and need not be, in any hurry 
to come to so-called “ final’’ conclusions 
hilst not attempting at this stage to justify the collateral 
working of Natural Selection amongst fossil plants, indicated 
broadly in many directions, simultaneously with that recognized 
amongst fossil animals, it may be worth while, perhaps, to add a 
further instance of the apparent a of Natural Selection 
_— fossil plants. 
sense) there was a succession of short internodes. At an early 
stage in Stylocalamites there was a series of pce as in 
sterile wi lola me a sing upwards in length. Thus in the Cala- 
marie@ the process, which was probably an adaptation serving 
to increase stectie was much more complicated, and it remained 
h 
eat arborescent Carboniferous genera (Lepidodendion Ci ae 
te), aE RTS factors have played a great part,* and the 
sary adaptation has been effected. 
> Biagerlogieal factors played as great a part in the differentia- 
tion of the two great groups of Angiosperms, namely mono- 
cotylous and dicotylous forms. Plants are, perhaps, more plastic 
than animals, and lend themselves to the influence of environment 
more obviously than the latter. eg may thus obscure morphic 
changes. Probably in no case are physical and morphic factors 
_—* found to act see of each aed. but ae one may 
mo 
Morphic changes are often the satkla: result of an antecedent 
hysical cause. the same time the reaction of an Rai an upon 
another may be quite invisible, and still morphic. It is owing fe 
se features and the existence of morphological valents, 
the existence of parallel but unrelated lines of development, that 
* Thus one is inevitably drawn to conclusions arrived at fa the Neo-Lamare- 
kian school, of which, through his elabotate study of south 1 Cephalopods, 
late Professor r Alpheus Hyatt was the f foremost exponent 
