Pl^nf RfP^f^HinO* comments on the exper- 

 r^ldllL UlC't^Umg iments of BURBANK «& 



NILSSON. By Hugo DeVries, Professor of Botany in the 

 University of Amsterdam. Pages, XIII by 351. 114 Illustra- 

 tions. Printed on fine enamel paper. Cloth, gilt top, $1.50 

 net; $1.70 postpaid. (7s. 6d. net.) 



Under the influence of the work of Nilsson,.Burbank, and others, the principle of 

 selection has, of late, changed its meaning in practice in the same sense in which it is 

 changing its significance in science by the adoption of the theory of an origin of species 

 by means of sudden mutations. The method of slow improvement of agricultural varie- 

 ties by repeated selection is losing its reliability and is being supplanted by the discov- 

 ery of the high practical value of the elementary species, which may be isolated by a 

 single choice. The appreciation of this principle will, no doubt, soon change the whole 

 aspect of agricultural plant breeding. 



Hybridization is the scientific and arbitrary combination of definite characters. It 

 does not produce new unit-characters; it is only the combination of such that are new. 

 From this point of view the results of Burbank and others wholly agree with the theory 

 of mutation, which is founded on the principle of the unit-characters. 



This far reaching: agreement between science and practice is to ftecome a basis for 

 the further development of practical breeding as well as of the doctrine of evolution. 

 To give proof of this assertion is the main aim of these essays. 



THE OPEN COURT PUBLISHINfi CO. 1522 Wabash Ave., Chicago, U. S. A. 



THE BEST W0RK5 ON FERNS 



OUR FERNS IN THEIR HAUNTS, by Willard N. Clute. Octavo. 333 

 pages. 225 illustrations. Eight colored plates. Contains the only il- 

 lustrated key ever published, and a full account of all the ferns of 

 Eastern America. The species can be identified by the illustrations, 

 alone. More copies of this book are sold annually than of any other. 

 Price post paid, $2.50. 



THE FERN ALLIES OF NORTH AMERICA, by Willard N. Clute. 

 Octavo, 250 pages. 15D illustrations, eight colored plates. A companion 

 volume to "Our Ferns in Their Haunts", containing a full account of the 

 scouring rushes, club-mosses, quillworts, selaginellas, water-ferns, etc.. 

 etc.. in North America. Seven keys to the species. A check list with 

 synonyms. The only book on the subject in the English language. 

 Listed in the New York State Library list among The Best Books of 

 1905. Price post paid, $2.00. 



SPECIAL OFFERS——— 



Either volume and a year's subscription to American Botanist .... $2.80 

 Either volume and a full set of American Botanist, (10 volumes).. . 6.00 



Both volumes to one address 3.80 



Both volumes and a year's subscription to American Botanist 4.50 



Both volumes and full set of American Botanist, (10 volumes) 7.75 



Address all orders to 



WILLARD N. CLUTE & CO., Joliet, Illinois 



