182 THE AUSTRALIAN NATURALIST. 
may be extracted and afterwards measured and analysed. 
Examination has shown that ordinary volcanic and metamor- 
phic rocks contain gas under considerable pressure, sufficient 
when liberated and measured at atmospheric pressure to oc-. 
cupy several times the volume of the containing rock In 
samples of schist, granite, gneiss, basalt, etc., examined by 
Prof. Tilden, the gases were found to range from 1.3 to 17.8 
times the volume of the rock, and consisted mainly of hydro- 
gen and carbonic acid. See Proc. Linn. Soc. N.S. Wales, 
32, p. 33, 1907.—Ed.) 
BOTANIOAL NOTES. 
(By E. Breakwell.) 
Drought-resisting Grasses.—The two grasses shown appear 
to be the commonest nutritious drought-resisting grasses in 
Nyngan district. They are Panicwm gracile, R. Br. and 
Neurachne Mitchelliana, Nees. Nyngan has had no rain for 
ten weeks, and the ground appears to be for a depth of nine 
inches devoid of moisture; yet the grasses (P. gracile, by its 
numerous long rootlets and V+ Mitchelliana by its bulbous, 
woolly roots) derive and conserve moisture sufficient for their 
maintenance. 
Poisonous Plants.—One poisonous and two reputed poi- 
ssonous plants may be seen growing in close association in the 
“monkey’’ country in Coonamble district, Vicotiana suaveo= 
lens, Lehm. (Wild Tobacco), Swainsona orcinotropis, F.v.M. 
S. luteola, F.v.M. The manager of Coonamble Government 
Farm informs me that only quite recently two cases of poi~ 
soning have been reported in his district from the tobacco 
lant. 
: Blennodia lasiocarpa, F.v.M., and another weed, 
Sisymbrium orientalis, are very common on waste and culti- 
vated lands at Nyngan Government Farm. On the areas to 
which sheep have access both plants are eaten down. 
“Hairy Heads’ (Z'richinium erubescens, Miq.). Mr. 
Fred. Turner, in his ‘‘Fodder Plants of Australia,’’ states 
that this plant may easily be detected among the surrounding 
vegetation by its lively green foliage. This is true, but it 
is no less conspicuous at present among the barren Wilga- 
Buddha scrub at Nyngan and Coonamble, by its striking 
inflorescence, which imparts a decided relief to the bare mo- 
notony of its environment. 
Helipterum floribundum, D.C. This weed comprises 
from 80 to 90 per cent. of the flora on railway areas, and 
adjoining lands at frequent intervals from Dubbo to Nyn- 
gan, a distance of 100 miles. Trustworthy graziers in- 
