Harper : Native weeds and their probable origin 359 



of new species hereafter might at least do a great service to their 

 successors by describing the habitats as explicitly and systemati- 

 cally as possible in every case. Habitat has been almost univer- 

 sally regarded by systematists as a matter of minor importance, or 

 ignored entirely ; but inasmuch as it represents the combined ex- 

 pression or resultant of geological history and all the properties 

 and adaptations of the species, its importance cannot be over- 

 estimated.* 



The following works (most of which have not been mentioned 

 in the foregoing pages), together with the references given in some 

 of them, bear more or less directly on the subject under discussion. f 



Blaringhem, Louis. Mutation et traumatismes. 1-248. //. 1-8. 



Paris, 1907. (From Bull. Sci. de la France et de la Belgique, vol. 



41.) Reviewed by W. C. W[orsdell] in Jour. Bot. 46: 201-203. 



Je 1908. 

 Dall, W. H. On a provisional hypothesis of saltatory evolution. Am. 



Nat. 11 : 135-137. Mr 1877. 

 Dawson, J. W. On the destruction and partial reproduction of forests 



in British North America. Am. Jour. Sci. II. 4: 161-170. S 



1847. (Deals especially with succession of vegetation in burned 



areas. ) 







Dunn, S. T. Origin of the deadnettles in Britain. Jour. Bot. 40 : 

 356-360. O 1902. Discussed by E. S. Marshall in the next 

 number (390-391). 



Dunn, S. T. A preliminary list of the alien flora of Britain. 1-30. 

 *9°3- (Not seen.) Reviewed in Jour. Bot. 41 : 141- 1 42. Ap 



J 



Mr 



1 



9°5- 



_ » 



Dunn, S. T. Alien flora of Britain, i-xiv + 1-208. 1906. (Not 

 seen. ) Reviewed by H. J. Riddelsdell in Jour. Bot. 44 : 138-142. 

 Ap 1906 ; and discussed by E. S. Marshall in same, 207-213. Je 

 1906. 



*In this connection pages 10-1 1 of Dr. B. L. Robinson's address on " The prob- 

 ems of ecology" (read before the "Congress of Arts and Science" in St. Louis in 

 l 9H, and reprinted in 1906 from the fifth volume of the proceedings of the Congress) 

 ar e well worth reading. 



t Some of these I have seen only in the library of the Staten Island Association of 

 ** and Sciences. For the privilege of examining most of the remainder I am in- 

 Cbted t0 th e New York Botanical Garden. 



