1905] CURRENT LITERATURE 149 
The following lectures outline the characteristics of elementary species, both 
in nature and in cultivation, and it is shown that natural selection must play a 
large part in determining their survival. Varieties are shown to differ from ele- 
mentary species in not possessing anything that is really new, and in originating 
commonly by the loss of some quality. Several chapters deal with the various 
kinds of varieties, retrograde, progressive, and ever-sporting; in the same connec- 
tion the subject of atavism is elucidated, as well as latent characters, and vicinism 
or variation under the influence of pollination by neighboring individuals. The 
lectures on mutations deal not alone with Oenothera, but as well with the peloric 
toadflax, double flowers, and a great many wild and cultivated plants that are 
supposed to illustrate mutation. A lecture that will be read with great interest 
by paleontologists, as well as others, is the one that considers the periodicity of 
mutations, and the relation that mutation bears to the length of geological time. 
The final lectures present the topic of fluctuating variations, and perhaps it is 
here that Darwinians will find least comfort in the work of DeVries. The 
closing words of the book, quoted from ARTHUR Harris, will be recognized as 
most apt: “Natural selection may explain the survival of the fittest, but it cannot 
explain the arrival of the fittest.” 
In a review of Die Mutationstheorie (Bot. GAz. 33:236-239. 1902), it was 
felt to be too soon to express an opinion concerning the place which that work 
Would occupy in the literature of evolution, although it was the reviewer's intu- 
ition that this place would be very high. Of the permanent value of that work, 
and of the work here under review, there is now no doubt at all. “The greatest 
contribution since DARWIN” is the universal testimony, and there is a feeling on 
all sides that the answers to many evolutionary questions are close at hand, and 
that through the application of experiment. To many of us the new volume 
brings more than did the old, because we have now seen the author face to face, 
and have perpetually in mind the modest, lovable man, as well as the renowned 
Investigator.—H. C. CowLes. 
MINOR NOTICES. 
EMERSON? has published the results of experiments in the control of the rust 
and scab of apples. He finds that the rust of apples due to species of Gymnospor- 
angium can be prevented by spraying with Bordeaux mixture if the first applica- 
oe is made when the gelatinous spore-containing projections first appear.on the 
‘cedar apples.” ‘This spraying should then be followed by a second spraying 
about ten days or two weeks after the first. He recommends also that the cedar 
apples be removed from cedar trees near orchards in the winter or early spring, 
and that where practicable cedar trees themselves should not be allowed to remain 
within one mile of apple orchards. The scab he found could be prevented by 
spraying twice with Bordeaux mixture, once just before the apple blossoms open 
and again just after the blossoms fall—E. Mrap WILCOX. 
* Emerson, R. A., Apple scab and cedar rust. Bull. Nebraska Exp. Sta. 88: 
PP. 21. figs. 9. 1905. 
