Natural Science 



A Monthly Review of Scientific Progress 



February 1899 



NOTES AND COMMENTS. 



Distribution and Morphology. 



Ix an essay of 6 pages, entitled " Grundziige der geographisch-morpho- 

 logischen Methode der Pilau zensystematik," (G. Fischer, Jena,) Dr. 

 Wettstein of Prague University has made a useful and suggestive 

 contribution to the literature of systematic botany. The scientific 

 systematist is no longer satisfied with adding new species or genera 

 to the roll of names ; he aims at establishing affinities between 

 those already known, in a word, the study of their phylogeny. 

 But there is great danger of losing oneself in theory and speculation, 

 and any objective method of comparison is welcome. Palaeontology 

 and ontogeny have proved of service in delimiting and deter- 

 mining the relationships of larger groups, as, for instance, the Fern 

 allies (Pteridophyta), and the Gymnosperms and the Angiosperms. 

 But in dealing with the higher subdivisions, genera, and species, 

 these are useless, and it is here that Dr. Wettstein steps in with 

 his geographic -morphological method. Morphology, though an 

 excellent guide to affinities, is not always trustworthy, as, for 

 instance, in the cases of seasonal dimorphism, which the author 

 has described in certain Gentians, and species of Euphrasia, where 

 late-flowering and early-flowering forms of the same species have 

 quite differently shaped leaves, and show also differences in stem- 

 development. 



The object of the essay is to show how facts of geographical 

 distribution may be used as a guide to the systematic arrangement 

 of the members of a polymorphic group of species. As examples, 

 Dr. Wettstein selects a group of European Gentians and Euphrasias. 

 Thus the range of fourteen European species of Gcntiana, section 

 Endotricha, is depicted on one map, and the result is confusion. 

 When, however, separate maps are devoted to each set of species, 

 the distribution areas of which adjoin, it is seen that there are 

 three distinct sets. As each set has, moreover, certain morpho- 

 logical characters in common, the author maintains that this combina- 

 tion of geographical and morphological considerations has elucidated 

 three natural groups, and emphasises this conclusion by subordinating 



7 NAT. SC. VOL. XIV. NO. 84. 93 



