240 BOTANICAL GAZETTE [MARCH 
have depended upon the unaided eye to detect reaction, and the work was 
done without the use of a clinostat. Methods of such crudeness must give 
questionable data. He states that Bacu’s results are not suited to test 
Van’t Horr’s law, but so far as they give data they indicate a coefficient of 
3-75. In contrast to this statement it should be mentioned that Bacu deter- 
mined the presentation time in the epicotyl of Vicia Faba for every two-degree 
change from 14° to 34°. This was done by accurate methods, and one must 
conclude that Bach’s figures are good for testing the application of the VAN’T 
Horr law between 14° and 34°. The following are the coefficients figured from 
Bacn’s table: 14°-24°, 3.88; 16°-26°, 4.61; 18°-28°, 4.54; 20°-30°, 3.80; 
22°-32°, 2.00; 24°-34°, 1.59. As is seen here, the coefficient is rather varl- 
able.—WILLIAM CROCKER. ‘ 
Anatomy of Welwitschia.—Miss Syxrs™ has investigated a large number 
of seedlings and young plants of Welwiischia, placed at her disposal by sie 
fessor PEARSON. The mature plant is aptly spoken of as an “adult seedling, 
since the main axis consists of root and much enlarged hypocotyl. Te 
ridges are developed by rapidly dividing parenchyma, the inner one bearing 
the strobiliferous axes. Each cotyledon is supplied by a pair of collateral 
bundles, which unite to form one pole of the diarch root, the transition being 
remarkably slow, probably on account of the great length of the hypocotyl. 
The four cotyledonary bundles are joined by the bundles from the buds, 
ridges, and leaves, this association of bundles forming four concentric groups, 
so that there is at no time any real stem structure. In the character eo 
cotyledonary bundles connected with a diarch root, Welwitschia is t 
with Araucaria and Podocarpus, and also in the details of the transition. Th 
small amount of primary vascular tissue is a remarkable feature, being limited 
to the root poles, the four cotyledonary bundles, and the four connecting 
hypocotyledonary bundles. In the base of the cotyledon, centripetal xylem 
is developed in connection with the two bundles, and of course the bundles 
traversing the hypocotyl become exarch. 
The retention of the seedling characters in the adult plant makes a ee 
parison impossible with the stem structure of other groups; and if the vascular 
structure of seedlings depends to a large extent upon “habitat and environ- 
ment,” as the author considers probable, a seedling comparison cannot be 
significant in indicating relationships. The result of the study, therefore, a4 
been to uncover some interesting facts in reference to the anatomy of ¥ ; 
witschia, rather than to uncover some much needed suggestion as to relation- 
ship.—J. M. C 
‘ It 
“4 Sykes, M. G., The anatomy of Welwitschia mirabilis in the seedling and adu 
States. Trans. Linn. Soc. London II. Bot. 7327-354. pls. 34, 35. figs. 5- 197° 
