Manchester Meiuozrs, T^o/. Ivii. (191 3), No. IG. 7 



One other point seems worth mentioning. I have 

 endeavoured to trace the origin of some of these delicate 

 lateral rootlets from the roots from which they sprang, 

 and in a number of instances have found such con- 

 nections. My object was to find out, if possible, the 

 orientation of the diarch plate of the rootlet to the axis of 

 the parent root. In the few cases in which it was possible 

 to observe this connection the diarch plate was found to 

 be vertically placed. Owing, however, to the defective 

 preservation of the tissues of the central cylinder referred 

 to above as well as to the frequent obiquity of the section, 

 it was not easy to select a very convincing section for 

 reproduction. I give, however, a camera lucida drawing 

 of one (^Fig. 5), in which the vertical plate of tracheids of 

 the emerging rootlet is fairly clearly seen. The interest 

 of this particular point in the anatomy of the rootlet lies 

 in the fact that Van Tieghem ' has pointed out that one 

 of the differences between the vascular Crygotagams and 

 the Phanerogams is to be found in the orientation of the 

 plate of tracheids of lateral rootlets. In the former the 

 plates stand horizontal, in the latter vertical. Lygino- 

 dendro?i would, therefore, in this particular agree with the 

 Flowering Plants rather than with the Ferns. 



I am aware that the facts concerning the root-apex 

 of Lyginodendron given in this communication may 

 appear to be somewhat meagre, but it seemed well to 

 put them definitely on record, as they are the result of an 

 examination of a very large number of rootlets, and so 

 far no detailed account of them has been given. Scott'" 

 refers to the apparent absence of a definite apical cell 

 which I had considered probable on first examination of 

 the only section then known to me which passed through 



^ Van Tieghem. Traite de Botaniqiie. 2« Edition, 1891, p. 705. 

 '" Scott, D. II. Studies in Fossil Plants, 1909, vol. ii., p. 3S7. 



