368 NATURAL SCIENCE. 



July, 



facts relating to this part of the subject ? Seeing, then, that 

 Stigmavia ficoides is absolutely devoid of any and every kind of 

 appendage excepting these organs, can anything but rootlets be made 

 of them ? Each one has the characteristic structure described in my 

 Monograph. They scarcely present the variations that might be 

 expected in a large number of individuals of the same organ. I have 

 certainly studied hundreds of thousands of these objects, and I 

 fearlessly affirm that, apart from the changes due to growth through 

 long periods of time, the organisation of one is that of them all. 

 Now, such being the case, are we to call these objects root-appendages 

 or leaves, because they cannot be both ? To begin with, their 

 symmetrical quincuncial arrangement forbids this. If, then, such 

 cannot be, if we determine to call them leaves, where are the roots of 

 the rhizome ? and, if they are rootlets, where are the leaves ? 



M. Renault boldly took the bull by the horns, and declared that 

 some of them were the one and some the other ; but this is sheer 

 nonsense. Assuming, then, as I do, that they are rootlets, what is to 

 be said for that argument ? Mr. Hick refers to M. Van Tieghem on 

 the subject ; now it was from M. Van Tieghem's paper on Symmetry 

 in Plants chiefly, I first learnt what is fundamental of my knowledge 

 on the subject of monarch, diarch, and other similar modifications of 

 this symmetry as it presents itself in roots and rootlets. At an early 

 period of my work I satisfied myself that the rootlets of Stigmavia 

 were examples of the monarch type of root. I at once sent him 

 specimens of these Stigmarian rootlets. He was not long in replying 

 " They are the monarch roots of a Lycopodiaceous plant ; " a decisive 

 reply of our highest authority on the subject. Mr. Hick thinks 

 he has settled the question by expressing the suspicion that these 

 rootlets may be collateral. It may strengthen his conviction when I 

 tell him that they are collateral, so far as the bundle consists of a xylem 

 and a phloem element arranged side by side, as he will see when he 

 consults fig. 52 of my Monograph, but their development from a 

 monarch tracheid, side by side with a pliloem element, was followed 

 by a subsequent series of processes that has no parallel in the living 

 Lycopodiaceae. The reason for this is obvious : the living forms have 

 no true exogenous development of a vascular zone. No one worth 

 naming now opposes the truth pronuilgated by me nearly twenty years 

 ago. In most of, if not all, the Carboniferous Lycopodiaceae, such a 

 growth was developed on an extensive scale. The tree, originally an 

 embryo produced from a minute macrospore, often lived to be more 

 than a hundred feet in height, and its stem attained to more than 

 three or four feet in diameter. Whatever may be the function of 

 the vascular tissues of its rootlets in connection with the absorption 

 of nutriment from the soil, they must have some function to perform^ 

 In a small seedling this work required but little machinery for its 

 performance, but when the embryo became an arborescent structure 

 even the rootlets were supplied with additional vessels, to enable 



