372 BOTANICAL GAZETTE [ NOVEMBER 
bud scales, whether in threes or twos, we have at least a suggestion that 
the “‘sport”’ was caused by the same influences which continue to affect if 
not to effect the alternation ; namely, on the one hand, the mechanical 
resistance which the growing papilla, which develop into leaves or 
branches, would ter were they to grow in certain easily recognized 
directions, and their freedom from this resistance if growing in other 
directions; or, onthe other hand, the disposal of the subjacent conduct- 
ing-tissues, which would affect the nutrition of the vegetating point, and 
so might favor the formation and growth of leaf and branch papille 
(Anlagen) in positions alternate rather than opposite to older or already 
developed parts. —GerorGE J. PEIRCE, Stanford University. 
HYGROMETER MADE WITH ERODIUM AWNS. 
[|THE following letter, together with some Erodium awns, was sent me a 
short time ago by Mr. Walter R. Shaw. I find upon trial that the awns are 
admirably fitted for the purpose indicated, and that the construction of an 
efficient hygrometer with them is a simple operation. Believing that others 
will be glad to make use of this method of demonstration, I have asked the 
privilege of publishing the letter and the sketch that accompanied it.—J. C. 
ARTH 
I have found the awns of Zrodium cicutarium an excellent substitute 
for those of Stipa in the Darwin transpiration hygrometer. E rodium is 
very common in some parts of Cali- 
fornia. A piece of iron wire bent in 
the form: of a tripod serves to support 
the awns in the crystallizing dishes bet- 
ter than the mechanical cross bars that 
were supplied some time ago- he 
seed on the awn is easily attached to 
Hygrometer made with crystal- be in- 
lizing dish, im which an Erctiun, 22S the advantage that it may © va 
epuigsin achpig le atripodformed stantly revolved to any position insi@ 
sees oe Sea Ee oe Oe the dish without throwing the aw? bea 
of the axis of the vessel. The Erodium 
awn carries its own pointer. On the whole, less dexterity is required 18 
its manipulation, and it has been shown to be more sensitive to humidity 
than the longer awns of Stipa ——Watter R. SHaw, Stanford University 
