14 



signifies only a small, limited portion of the complement of pos- 

 sible forms.' Such utterances, often enough already expressed, 

 are, notwithstanding the clear conception of species of our day, 

 still far remote from fruitful effect." 



The book, on the whole, is very suggestive along several 

 lines. It the first place, it shows how possible it is to arrive at 

 new and possibly important results merely by a reexamination 

 and reconsideration of the rich material already collected both in 

 herbaria and in published literature. In the second place, it em- 

 phasizes the great desirability of collecting and preserving in 

 herbaria unusual or abnormal forms, as well as so-called " typ- 

 ical " specimens. In the third place, it gives emphasis to the 

 value and absolute need of experimental pedigree culture, at 

 least as ancillary to morphological and systematic work, for the 

 reason that origin of species is more a physiological than a mor- 

 phological problem, and can never be solved by employing alone 

 the methods of comparative anatomy. 



Finally, added importance is attached to the "heliokomorphs" 

 as material upon which selection may act in the development of 

 new groups of the rank of species. In this connection, also, the 

 question of the heritability of acquired characters is forced once 

 more to the front. 



The burden of proof still lies with those who deny that species 



of plants as well as of animals, are formed in more than one way. 



As has been recently often stated, it is only by a combination of 



ecological and physiological studies that we may hope for a proper 



interpretation of the facts of comparative anatomy and ultimately 



of the method of organic evolution. 



C. Stuart Gager. 



Postelsia, reviewed in Torreya 6: 250. December, 1906, 

 may be obtained from Professor Josephine E. Tilden, University 

 of Minnesota, Minneapolis, Minn. 



