Februakt 23, 1906.] 



SCIENCE. 



295 



sent the significant structures in such a 

 form that he who collects may read. For 

 this reason large quantities of valuable ma- 

 terial have been in the past thrown aside 

 by the paleontological collector as undiag- 

 nosable. The skill of the lapidary- too has 

 often to be brought into play, before it 

 becomes possible to satisfactorily identify 

 a vegetable fossil or detect its affinities. 

 This state of affairs has brought it about, 

 that no such important results flowed from 

 the labors of the great French paleobot- 

 anist, Brongniart, as from those of his 

 more fortunate zoological contemporary 

 Cuvier. Indeed such anatomical observa- 

 tions as were made by Brongniart and his 

 more immediate followers were so mis- 

 leading that they resulted in the conclu- 

 sion that secondary woody growth was a 

 phanerogamic character and consequently 

 the mistake was made of putting the cala- 

 mites and sigillarians with the gymno- 

 sperms and not with their real affinities 

 the horsetails and clubmosses. This error 

 proved to be very tenacious of life and was 

 only finally overthrown towards the end 

 of the last century. 



The cheapening and improvement of all 

 kinds of apparatus, which is one of the 

 most gratifying features of modern scien- 

 tific progress, has made it possible in the 

 last decade or two to satisfactorily begin 

 the investigation of the past history of the 

 higher plants. Out of this study of the 

 structure of the more ancient vascular 

 plants, especially when carried on by those 

 adequately equipped for such a task, by 

 the knowledge of the anatomical structure 

 of allied plants still living, have emerged a 

 number of important general morphological 

 principles, which are destined to have an 

 influence on the development of botanical 

 morphology and phylogeny, not less impor- 

 tant than the investigation of Cuvier, in 

 the last century, on fossil animals, have 

 had on zoology. 



One of these important general prin- 

 ciples, namely, the repetition of phylogeny 

 in ontogeny is not confined to plants, but 

 has had few exemplifications heretofore on 

 account of the fact that our knowledge of 

 the past history of the vegetable kingdom 

 has been so woefully meager. Of this prin- 

 ciple one example will suffice. The re- 

 searches of the paleobotanists have made 

 us acquainted with the structure of a paleo- 

 zoic transitional group of gymnosperms, 

 the MeduUosffi. These had the numerous 

 concentric stem-bundles of many existing 

 ferns, but differed from these in the 

 fact that their bundles had secondary 

 growth. Their anatomical structure other- 

 wise strongly suggests the cycads, and 

 Potonie has expressed in fact the opinion 

 that the existing cycads have come from 

 this fossil stock. This view has recently 

 received a remarkable confirmation by the 

 discovery of the French anatomist Matte, 

 that in certain instances in the seedling of 

 the living cycadean genus Zamia, concen- 

 tric bundles resembling those of the Medul- 

 losse are present. Many other similar ex- 

 amples might be cited from recent litera- 

 ture. 



Perhaps the most important and most 

 novel general principle which has resulted 

 from the comparative study of living and 

 fossil vascular plants is the elucidation 

 of the tendency of ancestral character- 

 istics to persist strongly in the repi"0- 

 ductive axis or flowering stem. For ex- 

 ample, it has been pointed out by Graf zu 

 Solms that the arrangement and course 

 of the departing foliar traces in the cycads 

 is not of the complex type found in the 

 vegetative stem of the living genera of that 

 group, but of the simple tj^e occurring in 

 the leafy stem of the ancient cycadoidean 

 stock, the Bennettitales. Dr. Scott has 

 added to this the important observation that 

 in certain cases the structure of the bundles 

 of the cycadean reproductive axis resem- 



