172 THE AMERICAN BOTANIST 



was easy to decide what forms had departed enough from the 

 original to be regarded as separate species. The investiga- 

 tors looked for "natural units" around which to group the 

 insignificant forms which other authors had elevated to spe- 

 cific rank. An effort was made to get at the evolutionary 

 history and establish the degree of relationship between dif- 

 ferent forms according to the lines of descent. Viewed in 

 this light wholesale reductions were in order. In one case 

 eighty-three species and forms were reduced to variations of 

 a single variable species. The slender evidence upon which 

 many species had been made was brought out by tabulation of 

 their variations. The object of these reductions was to make 

 taxonomy and classification better serve the student ; to make 

 the naming of plants less difficult. It makes a great deal of 

 difference whether the type of a given group is regarded as 

 a species and all its allied forms sub-species and varieties, or 

 whether all are called species of equal rank. Moreover, to 

 have a proper regard for varieties is in line with our ideas of 

 evolution. Further studies of this nature, which the authors 

 promise us, will, we hope, make such work fashionable and 

 in time give us Manuals in which classification will mean some- 

 thing more than a mere list of apparently unrelated species. 

 The results of the present study have been published by the 

 Carnagie Institution of Washington. 



BOOKS AND WRITERS 



The fifth part of "American Plant Names" is about ready. 

 This will complete tlie list of species and leaves only the index 

 and finding list to be printed. * * * About ten thousand 

 common names are included. * * * "Rhus Dermatitis" 

 is the title of a new book by James B., McNair. * * * 



