242 BOTANICAL GAZETTE [MARCH 
Fossil plants.—PELouRDE’ has contributed the first published volume to 
the “Bibliothéque de re ”? which in turn is one of the 40 divisions of 
the “Encyclopédie scientifique’ under the general direction of TOULOUSE. 
Under Paleontology, 15 volumes are projected, 3 of which are to be on Paleo- 
botany. The two others will deal with gymnosperms and angiosperms 
e present volume is a compact summary of our knowledge of fossil 
cryptogams, all but 22 pages being given to pteridophytes. The completeness 
of the abr ate may be judged by the fact that the bibliography includes 256 
titles. J. .M. C. 
Identification of trees.—In order to meet the demands of teachers for a 
serviceable key for the identification of trees in their winter condition, the 
authors of Trees in winter have reprinted that portion of the volume containing 
the keys to genera and species.4 As indicated in the review of the ori 
volume,s these keys are based upon the bud, leaf-scar, twig, and occasionally 
upon the fruit characters. It is anticipated that the convenience of the key in 
a separate form will be appreciated as an important addition to the equipment 
for the winter study of our tree flora—Gro. D. FULLER 
NOTES FOR STUDENTS 
Self-sterility—CorreNns® has recently made the phenomena of self- 
sterility in plants the basis for a searching genetic investigation. After some 
preliminary experimentation, Cardamine pratensis was selected as the material 
best suited to his purpose, especially as some light had already been thrown 
upon self-sterility in this species by the investigations of Jost and HILDEBRAND. 
Correns began his study with two specimens of Cardamine pratensis, which 
though nt from the same source (Munster Botanic Gardens differed 
markedly in many characters, and were both self-sterile. These two plants 
(for convenience labeled B and G) were crossed reciprocally. The offs spring, 
in number, were tested out individually for self-sterility by pollinations 
(1) from the parents, (2) on the parents, and (3) from sisters. The results are 
given in such great detail and with such a large amount of easily follow 
tabular data, that no critic of modern genetic experimental work can criticize 
the evidence presented on the ground that the details are not all given, oF that 
3 PELOURDE, FERNAND, Paléontologic Lininy (Cryptogames cellulaires ¢t 
vasculaires). 16mo. pp. xxviii+360. figs. 80. Paris: Octave Doin et Fils. Fr. 5- 
4 BLAKESLEE, A. F., and Jarvis, C. D. ihe hea. of trees. Key to genera 
and species from “Trees j in winter.” Sto: p. 16. New York: Macmillan & Co. 
1913. 30 cts, For sale only by the eet Storrs, Conn. 
5 Bor. GAZ. 56:79. 1913. 
‘ Correns, C., Selbststerilitat und Individualstoffe. Biol. Centralbl. 33*3°7 
423. pls. 1-17. 1913 
