1901] CURRENT LITERATURE 71 
NOTES FOR STUDENTS. 
IN THE Gardener's Chronicle for November to last, Mr. W. G. Smith 
figures a curious malformation on the pileus of Agaricus albus, recently col- 
lected and now in the British Museum. On the lamellar surface of the 
obconical pileus there are five smaller pilei, each raised on a short stipe, 
arising almost in the same plane, midway from stipe to margin.—C. R. B 
CZAPEK’s recent paper ® upon the sensitiveness of the root tip to geotropic 
influence will be read with exceptional interest by all who have attempted to 
repeat, for class demonstration or otherwise, his ingenious experiments with 
bent glass caps. There appeared last year, in Russian, a paper by Wachtel? 
containing a mass of experimental evidence which the writer believed to dis- 
prove Czapek’s thesis entirely. Wachtel failed to obtain the curvatures 
described by Czapek for capped roots, and he obtained other curvatures 
which seemed to prove the absence of any localization of the sensitive region 
in such organs. Czapek has retraversed the whole disputed ground in his 
usual careful manner. He was able to reproduce all of Wachtel’s results 
and shows that they were due to imperfect manipulation in the preparation 
of the glass caps. The walls of Wachtel’s capillary tubes were too thin, 
thus bringing about either a narrowing of the bore at the angle, or the pro- 
duction of an angle too blunt for the desired purpose. Either of these con- 
ditions prevents the success of the experiment. The present article contains 
a translation into German of a good part of Wachtel’s paper, with critical 
remarks, and a discussion of the difficulties of manipulation, including a very 
detailed account of Czapek’s own methods. 
There is also added a new experimental proof of the fact that only the 
formative region of the root tip is sensitive to the earth’s gravitation. 
Briefly, this is as follows: Vertically placed roots are allowed to grow into 
right- -angled caps in the usual way; then the caps are removed, the seedlings 
placed upon the revolving klinostat, and their behavior is observed. Within 
a few hours a bending becomes evident, the after effect of the stimulus 
received by the stationary horizontal tip while still within the cap. Various 
Positions of the roots were tried and all point to the same conclusion. The 
new method is even more elegant than the older one, and in itself amounts to 
a proof of Darwin’s hypothesis of the localization of the sensitive region .,— 
Burton Epwarb LIvINGsTON. 
°CZAPEK, FRIEDRICH : Ueber den Nachweis mee oe Sensibilitat der 
Wurzelspitze. Jahrbiicher fiir wiss. Bot. 35: 313. 19 
WacutTeL, M.: Zur Frage iiber den Geotropismus der Wurzeln. Berichte der 
neurussischen iS leach der Naturforscher in Odessa 23 : 48. 1599. 
