474 



SCIENCE 



[N. S. Vol. XXXIV. No. 876 



such a polyphyletic descent, whether from 

 the more specialized anthrostrobilate Pteri- 

 dospermaj or from several groups of a 

 more primitive Cycado-Cordaitean plexus, 

 is more in accordance with the early dif- 

 ferentiation of the Cretaceous Angio- 

 sperms, and with the essential differences 

 existing now in the orders grouped to- 

 gether as Archichlamydeffi. 



Attempts at reconstructing the phylog- 

 eny of the Angiosperms are bound to be 

 at the present time largely speculative, but 

 we may possibly be on the threshold of the 

 •discovery of more certain records of the 

 past history of the higher Spermaphyta, 

 •since Dr. Marie Stopes has commenced to 

 publish her investigations of the cretaceous 

 fossil plants collected in Japan, and Pro- 

 fessor Jeffrey has been fortunate enough 

 to discover cretaceous plant-remains show- 

 ing structure in America. The former 

 have already provided us with details of 

 an interesting Angiospermie flower, and if 

 the latter have so far only yielded Gymno- 

 sperms, we may at all events learn some- 

 thing of the primitive forms of these 

 plants, the origin of which is still as prob- 

 lematical as is that of the Angiosperms. 



I trust that the criticisms I have made of 

 the theory put forward by Messrs. Arber 

 and Parkin will not be taken as a want of 

 appreciation on my part of the service they 

 have done in formulating a working hy- 

 pothesis, but merely as an expression of 

 my desire to walk circumspectly in the very 

 alluring paths by which they have sought 

 to explore the primeval forest, and not to 

 emulate those rapid but hazardous flights 

 which have become so fashionable of late. 



While the description of new and 

 often intermediate forms of vegetation has 

 aroused such wide-spread and general in- 

 terest in paleobotany, other and more spe- 

 cial aspects of the subject have not been 

 without their devotees, and have proved of 



considerable importance. Morphological 

 anatomy has gained many new points of 

 view, and our knowledge of the evolution 

 of the stele owes much to a careful com- 

 parison of recent and fossil forms, even 

 when these investigations have produced 

 conflicting interpretations and divergent 

 views. 



Another promising line of paleobotanical 

 research lies in the direction of investiga- 

 tions of the plant tissues from the physi- 

 ological and biological points of view. 

 Happily, the vegetable cell-wall is of much 

 greater toughness than that of animal cells, 

 and in consequence the petrified plant-re- 

 mains found in the calcareous nodules are 

 often so excellently preserved that we can 

 not only study the lignifled and corky tis- 

 sues, but also the more delicate parenchy- 

 matous cells. Even root-tips, endosperm 

 and germinating fern-spores are often so 

 little altered by fossilization that their cells 

 can be as easily studied as if the sections 

 had been cut from fresh material. It is 

 this excellence of preservation which has 

 enabled us to gain so complete a knowledge 

 of the anatomy of paleozoic plants, and 

 since the detailed structure of plant organs 

 is often an index of the physical conditions 

 under which the plants grew, we are able 

 to form some opinion as to the habitat of 

 the coal-measure plants. Though a begin- 

 ning has already been made in this direc- 

 tion by various authors, we have as yet 

 only touched the fringe of the subject, and, 

 as Scott points out in the concluding para- 

 graph of his admirable "Studies," the 

 biology and ecology of fossil plants offer a 

 wide and promising field of research. 

 Such studies are all the more promising, 

 as we now have material from such widely 

 separated localities as the Lancashire coal- 

 field, Westphalia, Moravia and the Donetz 

 Basin in Russia. 



Now that it has been definitely shown by 



