THE NATURALIST AND COLLECTOR 
1.6 
globose in form, whitish or pale yellow 
in color, filled with a soft white flesh 
which changes to an elastic substance 
of a yellowish-brown color. It grows 
to be twenty inches in diameter. 
THE PLUM. 
(Agaricus prunulus.) 
This edible species is easily distin¬ 
guished by the pure pink gills and the 
ringless stem. The stem and cap are 
white or sometimes of a light g'ray. It 
is to be found in damp woods, the cap 
growing to a diameter of six inches. 
(Lepiotct proeera) 
This mushroom is very abundant in 
the United States and is very agreeable 
in odor and flavor. The cap is ovate, 
with the cuticle thick and torn up into 
scales; in color it is brownish-yellow. 
The stem is from eight to twelve inches 
in length and of the same color as the 
cap. The gills are white, changing 
finally to a flesh color with a border of 
brown. The cap is from five to eight 
inches broad. 
[ To be continued. ] 
The question of the existence of 
water on the moon has been studied 
under favorable conditions at the Peru 
observatory of Harvard college. In 
addition to the ordinary r ‘rills,” Prof. 
Pickering has catalogued 35 narrower 
ones that he regards as river beds, 
these objects being but a few hundred 
feet in greatest width and a few miles 
long, and therefore not easily seen. 
The largest has its origin in the Mount 
Hadley rang'e of the lunar Appennines, 
follows a course a little north of west, 
and has a total length of 65 miles. 
There is no reason to believe that 
these valleys now contain water, but 
certain variable dark spots on other 
portions of the moon are held to indi- 
. cate water, although anomalies in 
their positions have suggested the 
more improbable hypothesis of vegeta¬ 
tion. It is stated that the changes in 
some of these spots—especially in the 
Mare Tranquilitatis—are perceptible 
to the naked eye. 
Some startling results, stated Lord 
Rayleigh, the other day at the Royal 
Institution, have been obtained in in¬ 
vestigating the sensitiveness of the 
ear to sounds. By one method he 
found that the ear is capable of re¬ 
sponding to an amount of condensation 
and rarefaction in the air equal to one 
twenty-millionth of an atmosphere, 
though by other experiments the 
amount seemed to be a tenth less. A 
point of some difficulty is, how do we 
know the direction of sounds. By trial 
he found that pure sounds, such as those 
of a tunig fork, tell their direction 
with certainty only when at the right 
or left; while with other sounds, such 
as those of the voice or of clapping 
the hand, the ear could easily judge 
the direction, wherever it was. 
Insects have a keen color sense. 
