386 BOTANICAL GAZETTE [NOVEMBER 
Several irregularities were noted, such as occasional imperfect dominance in 
combinations where one of the characters is usually fully dominant, but in these 
cases the blended condition in the first generation was followed by typical split- 
ting in the second. Length of ears and lop ears of rabbits were found to blend 
in inheritance, the second and subsequent generations retaining the blended or 
intermediate condition. 
The paper is illustrated with six plates of excellent halftone engravings, repre- 
senting the various coat characters and their hybrid combinations. Ten of these 
engravings with a few others are reproduced in another paper's by the same 
author, in which his more important results are used to illustrate the recent 
advances in our knowledge of the laws of heredity and their practical applications 
in plant and animal breeding. This paper was read before the American Breeders 
Association at its second meeting, at Champaign, Ill., February 1-3, 1905, and 
is also published without the plates in the Proceedings*® of that organization — 
G. H. SHULL. 
THE sympostum of six addresses on the mutation theory, delivered before 
the American Society of Naturalists at Philadelphia, December 28, 1994, has 
been published in full in Science. One of these addresses, which was published 
elsewhere, has already been noted in these columns."? CasTLE’® discusses 
subject from the standpoint of the animal breeding, illustrating with his results 
in guinea-pigs. He observed extra toes and long hair to arise as mutations and 
shows that long-haired and normal short-haired animals could coexist and inter- 
breed freely without ever swamping the long-haired condition, as it behaves . 
a Mendelian recessive. Natural selection could then determine which if — 
of these forms should be eliminated. If inheritance is not sharply alternative 
the mutation would simply act to increase the fluctuating variability and could 
never become a racial character through natural selection. ; 
In considering the relation of cytology to the mutation theory, ConxLIN® 
emphasizes the fact that all evolution must be the evolution of the germ = 
and is founded primarily upon cytological phenomena. The great morp 
complexity of the germ-cells which recent studies have demonstrated, and eh 
speaker’s observations on the diffusion of chromatin from the nucleus 
areas of the cytoplasm of the ascidian egg, are cited as favoring the 
15 CASTLE, W. E., Recent discoveries in heredity and their bearing on animal 
breeding. Pop. Sci. Monthly 66: 193-208. 1905. 
© Proc. Amer. Breeders’ Assn. 1:120-126. 1005. 
17 MacDovat, D. T., Discontinuous variation and the origin of sP 
reya 5:1-6. 1905; and Science N. S. 21:540-543- 1905- 
8 CasTLE, W. E., The mutation theory of organic evolution from the 
of animal breeding. Science N. S. 21:521-525. 1905. 
19 CONKLIN, E. G., The mutation theory from the standpoint of cytology: 
N. S. 21:525-529. 1905. ; 
ecies. Tor- 
standpoint 
Science 
