﻿142 BOTANICAL GAZETTE [FEBRUARY 



The geotropic response in jointed plants is the subject of an exten- 

 sive article by Miehe,^ who has added much to the work done in this field by 

 Kohl^° two years ago. Tradescantia and Zebrina were used in a long series 

 of experiments, which, however, cannot be even outlined here. Miehe 

 believes he has shown that Kohl's conclusions are not well founded. Kohl's 

 work seemed to show that two nodes were necessary for bending, the 

 upper acting as a perceptive region while the lower was responsive. Thus 

 in a cut portion of stem the apical node did not bend, but bending occurred 

 in all nodes behind this. Miehe's explanation of this and other observed 

 phenomena is that we have here to deal with an inhibition of the geotropic 

 response in the node nearest the cut. He shows that various other factors will 

 influence the geotropic response in a similar way. Three terms are pro- 

 posed to describe these and kindred phenomena: kafaionus^ to denote a 

 checking of power to respond normally ; anatoniis, an acceleration of this 

 power; and metatonus, a complete reversal of the response. From the 

 present paper it may be regarded as certain that the case is at least not so 



simple as was thought by Kohl. — Burton E. Livingston. 



Hegi" presents the historical features of the flora of a limited area lying 

 within the cantons of Zurich, St. Gall, and Thurgau, Switzerland. The 

 Miocene fossils indicate a subtropical climate at that time, while the plant 

 remains associated with the interglacial beds record the climatic and floristic 

 changes incident to the Pleistocene conditions. After the final retreat of the 

 ice-sheet the associated non-glaciated areas contributed the various species 

 which characterize the area in question today. The '* xerothermische'* 

 floristic element from the Mediterranean region was at first perhaps the 

 most effective, since the extreme cold of the Pleistocene times was appar- 

 ently followed by a period of aridity and comparatively high temperatures. 

 With the advent of the present climatic conditions the "silvestre" element 

 (forest trees and associated vegetation) from the region northeast of the 

 Caspian sea, became the dominant vegetative covering of the area. A third 

 element of the flora is the class known as " glacial relicts" which, while 

 numerous as to species, is limited as to distribution and the number of 

 individuals. A considerable portion of the paper is given over to an anno- 

 tated list of the present flora, which is based largely upon the author's 

 personal collections and observations. — J. M. Westgate. 



Interesting studies on the effect of centrifugal force upon seeds and 

 plants, with respect to both the arrangement of cell parts and the later effect 



9 Miehe, Hugo, Ueber correlative Beeiuflussung des Geotropismus einiger 

 Gelenkpfianzen. Jahrb. Wiss. Bot. 37: 527-593. ph. 12, 13a, 13b, 1902. 



*°KoHL, F., Die paratonischen Wachsthumskriimmungen der Gelenkpfianzen. 

 Bot. Zeit. 58: 1-28. pis, 2, 1900. 



"Hegi, Gustav, Das obere Tosstal und die angrenzenden Gebiete fioristisch 



und pflanzengeographisch dargestellt. Bull. Herb. Boiss. II. i : 179. 1900; 2' 

 216. 1901, 1902. 



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