BOTANICAL SUBJECTS. 177 



From a conventional point of view, to regard the \ine tendril 

 as homologous with a root seems preposterous, considering that 

 it bears stipules. But my contention is that it has stipules because 

 it is a branch which developed in the air, and not a branch 

 developed in the soil. If the vine stem were a creeping rhizome 

 it would probably have at each node a leaf turned uppermost, 

 and opposed to it a root growing into the soil.* As, however, 

 the stem is erect, the same elements continue to be inherited. On 

 one side we have a leaf, and opposed to it a root, transformed into 

 a tendril, which is another term for an organ of attachment, like 

 the roots of many seaweeds, and the aerial roots of orchids. 

 Why the vine tendril should become a different thing because the 

 stem hajDpens to be erect, and because this particular branch has 

 been called a tendril, I do not in the least see. It seems to me 

 that we think too conventionally, while in nature the only 

 conventionality appears in the way of heredity. 



The tendrils of Vitis often terminate in flower-buds, and the 

 whole bunch of grapes would therefore be nothing but a very 

 compound tendril, with each sub-division ending in a flower-bud 

 and subsequently in a grape. When they do not end in flower- 

 buds the ends bear a slight disk-like enlargement. 



The tendrils of Ampelopsis are like those of the vine, furnished 

 with minute stipules. But in the former, each sub-cUvision ends 

 in a berry-like sphere, which afterwards becomes the disk of 

 attachment, such as we see in the seaweeds called Cystophora 

 Sonderi (Fig. 43), PolysijDhonia rostrata (Fig. 46), and others. 

 The disk of seaweeds I have shown is only a fused mass of root- 

 flbrils, or the roots are only a fimbriated disk (vide Polysiphonia 

 and Caulerpa (Figs. 46 and 47). We may therefore regard the 

 tendril of Atnpelopsis, with its berry-like endings, also as an aerial 

 root. The inference to be drawn from this interpretation would 

 be that the bunch of grapes, the vine tendril, with or without 

 its teriiiinal expansions, and the tendril of Ampelopsis are all 

 homologues. Further, we would have the Ampelopsis disks 



* In the Naval Exhibition there Avas a vine on the wall of the printing 

 room. Its branches projected from the wall. All the tendrils of these 

 branches were directed downwards, and all the leaves upwards, towards the 

 skylight. 



A p. 1724. ^ 



