212 THK PI.ANT WORI.D 



On June 28 Professor Hugo de Vries began his lectures in the summer 

 school of the University of California, at Berkeley, on the "Theory of 

 the Origin of Species and Varieties by Means of Mutation." In contrast 

 with the larger part of Darwin's followers, De Vries assumes that slow 

 and gradual development has not had any prominent part in the evolu- 

 tion of organisms in general. He pointed out that in the evening prim- 

 roses species and varieties are originated by sudden leaps and repeatedly, 

 each new form arising in quite a number of individuals from the old stock, 

 at once and without preparation as intermediates. The stock itself is not 

 changed by the process, as it would be by those slow and gradual changes 

 which are assumed by Wallace and others to occur. 



The lectures have to deal with the occurrence of elementary species, 

 constant varieties, ever-sporting or inconstant varieties, mutation and 

 fluctuation. They are attended by about sixty students, which is an 

 exceptionally large number when compared with that ordinarily in at- 

 tendance at science lectures. It is to be hoped that the lectures will be 

 published as a whole, in order that Professor de Vries may be enabled 

 to reach the attention of the many students of biology in this country. 



Book Reviews. 



New England Ferns and their Common Allies. By Helen Eastman. 

 Boston and New York : Houghton, Mifflin & Co. 



This is an attractiv^e little volume which will doubtless serve a useful 

 purpose in introducing many to the study of these interesting plants, and 

 as such should find a wide sale. Beginning with an enumeration of the 

 fruiting season of the several species of ferns, followed by a list of the 

 preferred habitats and hints to beginners, we come to the body of the 

 work, in which the forms are taken up in systematic order. The common 

 and scientific names are given, together with a brief but fairly complete 

 description, with the size, place where usually found, and often a bit of 

 history, etc. The illustrations, which are fairly numerous, are said to be 

 by an entirely new and original process, but which seems to be merely 

 one of shadow-printing. Some of these illustrations are pretty good, but 

 many are nearly worthless for purposes of identification. Occasionally 

 a slip is noted, as when the green spleenwort i^Aspleyiiuni viride) is said 

 to be confined to the mountains of Vermont. The book is attractively 

 printed and will doubtless be found useful to would-be students. 



F. H. K. 



