472 BOTANICAL GAZETTE [DECEMBER 
genes. There is a growing sentiment that all hereditary phenomena must rest 
in last analyses upon a chemical basis. DARBISHIRE?+ has made a careful exam- 
ination of the starch grains of round and wrinkled peas in pure-bred strains and 
in several generations of their hybrids. He finds that there are several uncor- 
related features of these starch grains which result in the hybrids having some of 
the characteristics of the starch grains of both the parents, thus tending to obscure 
the fact that the segregation of the starch characters is perfect. 
Miss WHELDALE?S has studied the floral pigments of a large number of 
species, devoting her attention most intently to the anthocyan series, but also 
including a discussion of xanthein, xanthin, and carotin. A useful summary 
is given of the studies of others upon the chemical composition of these com- 
pounds, and a large number of observations from her own analyses are presented, 
the general result being to show that there is a very large number of different 
pigments having a common fundamental structure, which pass under each of 
these several names. From these analyses and from experience in cross-breeding: 
she concludes that at least two features are necessary to the production of the 
anthocyan color: the one a colorless aromatic chromogen of the flavone series, 
the other an oxidizing agent which she believes to be a ferment. The details of 
Miss WHELDALE’s methods of analysis and the lengthy list of literature will prove 
of great value to students who desire to go into these more intimate problems of 
genetics. : 
A similar work from the animal side has been attempted by RipDLE,”° with 
respect to the melanin compounds, though the author presents no work of his 
own, simply bringing together in an instructive way the more recent results of 
investigations in this field. One unfortunate feature of Rippie’s work is his 
unfamiliarity with the Mendelian work from the experimental point of view. He 
thinks that he has proved the utter fallacy of the entire body of Mendelian teaching, 
and that he has demonstrated the continuity of the so-called unit characters, @ 
statement which contravenes the experience of all investigators who have studied 
the behavior of pigment characters in actual breeding. No epigenetic hypothesis 
as yet gives the slightest hope of enabling such predictions as are successfully 
made continually by workers with the unit character conception.—GEORGE H. 
SHULL 
Perception of light.—HAseRLANpT?7 attempts to strengthen his theory of 
light perception by plants, especially on the physiological side, acknowledging 
HIRE, A. D., On the result of crossing round with wrinkled peas, with 
especial reference to their starch grains. Proc. Roy. Soc. London B 80:122-135- 1908. 
25 WHELDALE, Miss M., The colors and pigments of flowers, with special reference 
to genetics. Proc. Roy. Soc. London B 81:44-60. 1909. 
———, On the nature of anthocyanin. Proc. Cambridge Phil. Soc. 15+ 137-18 
1g0Q. 
26 RIDDLE, O., Our knowledge of melanin color formation and its bearing on the 
Mendelian description of heredity. Biol, Bull. 16: 316-351. 1909. s: 
27 HABERLANDT, G., Zur Physiologie der Lichtsinnesorgane der Laubblatter. 
Jahrb. Wiss. Bot. 46:377-417. 1909. . 
