454 Dr. F. A. Bather— Prof. Nathorst's Studies of Fossil Plan fs. 



a fairly good flowing line and be sufficiently in accord with the 

 direction of the tide. I assume that the training-walls are up to the 

 level of low water only, so that the tide or flood- stream can pass 

 freely over them. Let either of these conditions, expressed in Figs. 4 

 and 5,' be fulfilled and the low- water channel will be permanent. If 

 the contrary can be shown, I shall have to admit that I am wrong. 



\ i T 7 r \ \ 



Diagrams of Eivers with Stable Channels. 



Fig. 4. — Tributary streams coming in on one side only ; none at the crossing of the 

 channel. 

 ,, 6. — Tributary streams directed by training- walls to fixed points on either side 

 of the intended channel. 



VII. — Kathokst's Methods of studying Cutinised Portions ok 



Fossil Plants. 



By F. A. Bather, D.Sc, M.A., F.G.S., etc. 



BOTANISTS who study the tissues of living plants, or those palaeo- 

 botanists who deal with actual petrifactions, have scarcely any 

 idea of the difficulties that meet the worker on carbonised plant- 

 remains, especially when the material is so limited that the research 

 cannot be repeated in the event of damage to a single preparation. 

 Moreover, the research can be conducted only on those portions of 

 the tissue that are cutinised, since all the rest have been carbonised or 

 destroyed in the course of fossilisation, and no longer appear after the 

 preparations have been bleached. The student of Mesozoic plants 

 is in the further unhappy position that, with a few notable exceptions, 

 he rarely finds portions of the plant that show any structure ; he in 

 particular must direct his attention to the cutinised membranes, and 

 above all to the cuticle of the leaves and stems and, in the case of 

 Pteridophyta, to the spores. 



So long ago as 1856, J. G. Bornemann, in his memoir "Ueber 

 organische Reste der Lettenkohle Thiiringens," described some 

 cuticles, which, thanks to the maceration of the leaves in the 

 course of fossilisation, had been preserved in such a way that they 



* For these two diagrams and for Taluable assistance I am indebted to a young 

 engineer, Mr. W. E. Jamee. 



