17 



both because of its biological relations and of its traditional 

 status. Again, as a product of press work this volume is an 

 impressive one, the more so because it bears the stamp of the 

 University of Illinois as publisher and thus serves to emphasize 

 the state university in its more recently assumed role of promoting 

 research and of publishing the results of research. The greater 

 bulk of the volume is comprised in an exposition of photo- 

 illustrations which deserves special comment and commendation. 

 There are 245 plates including a full-size illustration of charac- 

 teristic portions of each species and 237 or nine-tenths of all the 

 forms recognized are here illustrated for the first time. "It has 

 been my aim (quoting Professor Trelease) to picture the more 

 essential features of every species without alteration of size, by 

 aid of the camera and if possible from type specimens." Mani- 

 festly such a thoroughgoing enterprise necessitated the vis- 

 iting of all the major herbaria of America and Europe and a 

 very generous attitude toward the use of specimens for these 

 photo-illustrations. "That every species has been figured . . . 

 may be my excuse for adding that words are lacking to express 

 adequately my gratitude to the many botanists of Europe and 

 North America who have opened their collections to me without 

 restrictions, and in some cases have allowed type material to 

 follow me across the Atlantic or have replaced photographs which 

 were unsatisfactory in the first instance." 



With regard now to the species and varieties of Phoradendron 

 segregated by the author it will no doubt appear to many 

 botanists that the multiplication of forms has gone beyond the 

 point which any one not a specialist in the group can follow. 

 Especially will this be the case if it finds one at the beginning 

 point of contact with the genus where "all mistletoes look alike." 

 The present reviewer, for example, while not possessing the taxo- 

 nomist's powers of discernment, still has had a fairly extended 

 field contact with a limited aspect of the genus (on the boundary 

 between southern and southwestern territory), would scarcely 

 have anticipated the possibility of segregating (under the section 

 flavescentes) as many as twenty-three species and varieties out of 

 the old Phoradendron fiavescens. Nevertheless, every man who 



