No. 390.]} REVIEWS OF RECENT LITERATURE. 521 
further response to that particular strength of stimulus is possible 
This individual attunement may persist, and may be inherited and 
thus initiate a racial attunement. 
The author does not claim that this is a complete explanation of 
the facts. It is merely a tentative hypothesis. But it is almost too 
soon to attempt even an hypothesis, for if we try to compare the 
critical points of the various kinds of stimuli in their effects upon 
the rate and the direction of growth, in order to see what rela- 
tion exists between them and how they are related to adaptive 
responses of the organism, we find the data often contradictory and 
always inadequate. For example, if we compare the tables given on 
page 439, we find that of the seven species mentioned in Table 45, 
only four are to be found in Table 46. Moreover, the first mentions 
the organs affected, while the second leaves us in doubt as to whether 
we are dealing with root or stem. Similar difficulties arise in an 
attempt to compare the table on page 454 with those on pages 464 
and 465. All this goes to show that, in spite of all that has been 
done, more work is needed, and the author’s hypothesis will be of 
value if it serves no other purpose than to stimulate research from a 
broad point of view. 
We notice few errors and omissions. On page 411, line 4, for 
plant read cylinder. The important work of Martin and Frieden- 
wald' on the effect of light upon metabolism in animals has been 
overlooked. On page 440 a diagram of the spectrum is given, 
showing an interesting coincidence between the point of maximum 
retardation of growth and that of no phototropic effect. But this 
coincidence is not mentioned in the text. R. P. B. 
Variation Statistics. — In this work Duncker provides natural- 
ists with the new tool which the English anthropologists, zoölogists, 
and mathematicians have developed. Many of the works of the 
mathematicians, especially the invaluable treatises of Pearson, have 
been beyond the mathematical training of most biologists. In this 
paper the results of these treatises are given in a comparatively sim- 
ple fashion. Great stress — relatively too much in the reviewer’s 
opinion — is laid on the methods of constructing the various types of 
1 Martin, H. N., and Friedenwald, J. Some Observations on the Effect of 
Light on the Production of Carbondioxide Gas by Frogs, /. Æ. U. Studies, iv, 5, 
p- 221, 1889 
2 Duncker, G. Die Methode der Variations- TAN A : hud Entwickelungs- 
mechanik der Organismen, Bd. viii, pp. 112-183. Feb. 2 
