Influence of the Adult Plant upon the Seedling. 319 
ON THE INFLUENCE OF THE STRUCTURE 
OF THE ADULT PLANT UPON THE SEEDLING. 
By T. G. Hill and E. de Fraine. 
[With 3 Diagrams and 9 Text-Figs.] 
N much, if not in all, of the recent investigations upon the 
anatomy of seedlings, the influence of the general morphology 
of the adult plant—which mainly depends upon physiological 
necessity—upon the seedling has not been appreciated. 
That such an influence is exerted cannot, we think, be denied ; 
although, naturally, it is only by the study of those plants shewing 
marked peculiarities that the phenomenon is at all conspicuous. 
And not only may the characteristic external morphology be thrust 
back, as it were, into the seedling—that is into the embryo—but 
the same holds for anatomical peculiarities. 
To take a few examples: in Convolvulus tricolor and in certain 
Solanacece, Datura Stramonium for example, plants in which the 
vascular cylinders of the epicotyledonary axes are characterized by 
medullary (intraxylary) phloem, it is found that in the cotyledons 
and hypocotyls this same peculiar anatomical character obtains. 
In Mirabilis 1 there are similar points of correspondence in 
anatomical details: a characteristic feature of the stem-structure of 
the adult is the polycyclic arrangement of the vascular bundles, 
some of which may be bicollateral or even concentric ; the hypo- 
cotyl exhibits similar phenomena. 
Salicornia , 2 as is well known, has a very distinctive appearance. 
The succulence of the stem of this plant is due not to cortical 
tissue, but to the foliage, the basal portions of which form 
decurrent sheaths around the axis. Almost exactly the same thing 
is found in the seedling; the cotyledons are very small and fleshy, 
and fuse laterally to form a tube the base of which is decurrent 
down the hypocotyl, thus forming the so-called succulent “cortex.” 
Further, the distribution of the leaf-traces is the same in the adult 
and in the seedling: to each leaf, or cotyledon, a single vascular 
bundle passes out from the node and branches into three; of these, 
the median strand supplies the tip, whilst the two lateral bundles 
curve outwards and pass downwards, their branches supplying the 
1 Hill and de Fraine. On the Seedling Structure of Certain 
Centrosperma:. Ann. Bot., 1912, XXVI. 
2 Hill and de Fraine, loc. tit. 
