256 BOTANICAL GAZETTE [APRIL 
permeability of the limiting membranes of the protoplasts or of 
the vacuolar sacs. 
Experimental studies such as are here described lead the inves- 
tigator into the consideration of two phases of the subject. One_ 
is concerned with the demonstration of induced hereditary altera- 
tions and the study of their behavior in pedigreed strains, in hybrid- 
izations, and under various environic conditions. The other 
includes a consideration of the mechanism by which an environic 
agency affects the physical bearers of heredity. Both compre 
some important and interesting possibilities in evolutionary science. 
DESERT LABORATORY 
Tucson, ARIZONA 
EARLIER PAPERS BY THE AUTHOR ON RESULTS OF OVARIAL 
TREATMENTS 
Heredity and the origin of species. Monist, Jan. 1906; reprinted in 
advance Dec. 1905, and as Contribution No. 80 of the New York Botani- 
cal Garden, 1906. 
Heredity and environic forces. Vice-presidential address before Section 
G, A.A.A.S., at Chicago meeting, Dec. 30, 1908; reprinted in advance 
of annual wohoiie: - 
3- Heredity and eS origin of species. Smithsonian report for 1908, PP- 503 
523; issued in oak: 
Physiology of cnet Sixth year book, Carnegie Institution of 
ington, p. 62, 1907; seventh year book, p. 63, 1908. 
5: Mites c in rie slated by ovarial treatments Highth year book; 
Carnegie Institution of Washington, p. 59, 1 oe 
6. The direct influence of environment. Filty pe of Darwinism, Pp. 144 
1908. 
Origination of self-generating matter and the influence of aridity upon is 
evolutionary development. Outlines of geologic history, by WILLIS 
SALISBURY, p. 278, 1910 fe 
- Environic response. Amer. Nat., Jan. 1911; also Science, Jan. 20, 1gtl. 
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EXPLANATION OF PLATES XIV-XVI 
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Pirate XIV.—A, rosette of Oenothera biennis at Desert Laboratory, 19 
B, rosette of induced derivative. leaf from 
PLATE XV.—Oenothera biennis: 1, leaf from young rosette; 2, ¢ er 
rosette four months old; 3, leaf from lower part of mature rosette; 4 
