ZOOLOGY AND BOTANY, .MICROSCOPY, ETC. 373 



absent. Each of the four verticils is served by a well-marked wood and 

 bast system. 



The unisexuality of Clnetales arises from an original hermaphroditism 

 by abortion, and, as Hooker remarks, the male flower (pseudo-hermaphro- 

 dite) of W. mirabilis is an evidence of this. The verticils show two 

 divisions, except in the female flowers of Ephedra, which shows three. 

 This suggests that there has been a change in the floral symmetry of the 

 Gnetales. 



The authors conclude that these flowers are Angiospermous, and in a 

 state of retrogressive development. By reason of the many gymno- 

 spermic characteristics which they retain, they are primitive Angiosperms. 

 They have nearly the same floral organization as is found in Amentales, 

 and so would form a side group parallel with this family, and belonging 

 to a lateral branch from the base of the Angiosperm trunk. Amentales 

 may possibly have arisen from the base of this branch. 



Physiology. 

 Nutrition and Growth- 



Removal of Starch through the Petiole.* — N. T. Deleano has 

 experimented with Vitis vmifera in order to discover the method of con- 

 duction in the petiole of the products of assimilation of the leaf. The 

 author applied the iodine-test under very varied conditions. In some 

 cases the leaves were left intact until the application of the test ; in 

 others they were placed in the dark with either the upper or lower 

 surface resting upon water. Sometimes the petioles were immersed in 

 water or portions of them cut away ; they were also treated with chloro- 

 form-water or plasmolyzed. The results show that leaves left on the 

 stem lose their starch most quickly ; but this loss is retarded when the 

 upper surface of the leaf, and still more when the lower surface is laid 

 on the surface of water. When the petiole is split longitudinally, the 

 starch disappears at the same rate from both halves of the leaf. If, 

 however, a transverse cut is made in the petiole so as to pass through 

 half of the vascular strands, the starch disappears more slowly in that 

 half of the leaf in which these strands are cut. Starch is apparently 

 removed from the leaf chiefly through the vascular tissues, but it is still 

 uncertain whether the wood or the bast is the more important factor. 

 In a scalded stem the starch was conducted more slowly than in an 

 uninjured one. Petioles placed in saltpetre solution were unaffected in 

 44 hours when the solution was of 5 to 10 p.c. concentration. In 

 52 hours, with a concentration of 10 p.c, plasmolysis occurred, but the 

 petioles died. Chloroform-water retards the passage of starch through 

 the petiole. 



The author is of the opinion that no definite conclusion can be 

 formed as to the amount of conduction that takes place in the cortex. 



Irri ability. 



Effect of Longitudinal Compression upon the Production of Me- 

 chanical Tissue in Stems. f—L. H. Pennington reports that the woody 



* Jahrb. wiss. Bot., xlix. (1911) pp. 129-86 (7 figs.). 

 t Bot. Gaz., 1. (1910) pp. 257-84. 



