154 FORESTRY [Bot. Absts. 



the maternal brood-pouch, contained on the dorsal side of the shell in the heart region, 1, 2, 

 or 3 little dents, which disappeared after the first ecdysis. The last time these dents had 

 been noted was in the year 1911. — During the years 1911-1918 this character disappeared in 

 the stock (cultures have been examined weekly), but in October 1918 a young Daphnia was 

 born with an unmistakable chitin dent, the progeny of this animal being dentless again. — 

 The reappearance of this character after being lost for seven years proves that although this 

 phenotypic character has disappeared, the genotypic constitution of these laboratory-bred 

 animals had undergone no change. — M. A. van Herwerden. 



1044. Van Herwerden, M. A. De invloed van radiumstralen op de ontwikkeling der 

 eieren van Daphnia pulex. [Effects of the rays of radium on the oogenesis of Daphnia pulex.] 

 Genetica 1 : 305-320. July, 1919. — Dutch version of a paper on the same subject published in 

 Versl. Kon. Akad. Wet. Amsterdam 20 4 : 1918— See Bot. Absts. 2, Entry 961— G. H. Shull. 



1045. Weatherwax, Paul. The ancestry of maize— a reply to criticism. Bull. Torrey 

 Bot. Club 46: 275-278. July, 1919. — Refutation of hypothesis advanced by J. H. Kempton 

 and G. N. Collins regarding hybrid origin of maize. Author believes development by gradual 

 evolution better explanation. — R. J. Garber. 



1046. Whiting, P. W. Two striking color variations in the green frog. Jour. Heredity 

 10: 127-128. Mar., 1919. — The many variations in color of the green frog, Rana clamitans 

 Latrielle, are explained by Mary C. Dickerson in The Frog Book. Green color is produced 

 as the result of black and yellow pigments and a structure, the so-called interference layer, 

 which is a single layer of polygonal cells between the epidermis and black pigment. 

 These cells contain the yellow pigment, but if they were empty the black pigment would be 

 seen through them, — making the color blue, due to the absorption of the longer light rays. 

 When the interference cells contain yellow, the blue is seen through the yellow and the result 

 is green. Changes in color are due to the expansion or contraction of the black pigment 

 which presses close to the interference layer, thus diminishing the density and giving a brown 

 color and vice versa. — Two color variations have been noted; one in which the yellow pigment 

 was entirely lacking and the black reduced to a very light sepia, the skin appearing creamy 

 white. This variation is apparently comparable to that described by Haecker in the tiger 

 salamander. The other variation was a young frog lacking black pigment entirely, the 

 skin being a clear light yellow, the iris clear gold, the pupil pink. These phenomena may be 

 explained, employing Sewall Wright's theory of two enzymes for color inheritance in mam- 

 mals, by extending it to amphibia. — M. J. Dorsey. 



1047. Woods, F. A. Good qualities are correlated. Jour. Heredity 10:84-86. Feb., 

 1919. — A review of the evidence tending to show that individuals which possess rare and 

 desirable qualities in one line are also capable in other lines. The importance of this con- 

 ception is emphasized in view of the fact that some writers have held that there is consider- 

 able uncertainty of success in attempting selection within a race, if when there is improve- 

 ment in one direction there is retrogression in another. — M. J. Dorsey. 



1048. Worsham, E. Lee. Twentieth annual report of the State Entomologist for 1917. 

 Georgia State Bd. Entomol. Bull. 51. U p., 1 pi., 2 fig., 1 map. 1919. [See Bot. Absts., 

 Entry 378.] Tests of a number of varieties of cotton, with respect to their yield, length of 

 fiber, resistance to wilt, and earliness of maturity are described. Some of the varieties are 

 named and the results tabulated. — A. Franklin Shull. 



