On Fibrous Covering. 
281 
first frame had grown through the covering; under that six inches 
high, the grass had increased about 5 inches in lengtli above that of 
the other parts of the field, and was rapidly making its way to touch 
the covering ; under the covering 1 foot high the grass had grown about 
3j inches; under that placed 2 feet above the ground, the grass 
had increased only about \\ inch; and under that of 3 feet elevation 
there was simply a discoloration, marked by a definite outline : the 
grass was darker, looked stronger and thicker, but was not of sufficient 
length above that surrounding it for the difference in length lo be mea- 
sured. Under the straw laid on the grass it had increased about 3 to 4 
inches. The most rapid growth was that under the covering placed 3 
inches above the ground. Mr. Gurney, at our next meeting, communi- 
cated the result of a series of experiments made to ascertain how far 
light influenced this action. " Rods of transparent glass were used, 
instead of wood or reeds, in one part ; and rods of wood and branches 
of trees in another. The same increase of growth was observed under 
each— under the glass and under the opaque bodies, also under some 
semi-opaque covering." These experiments, he said, required repeti- 
tion ; for there were some foreign influences which might have affected 
the results. 
" A piece of grass land had been covered during the day, from six 
o'clock in the morning to six at night, and left uncovered during the 
night, for several weeks. Another piece lying adjoining had been 
covered by night and uncovered by day during the same period. The 
first piece — namely, that uncovered by night and covered by day — soon 
changed colour, put on a deep green (peculiar to the eflfects of Gur- 
neyism), and rapidly increased in length ; but the piece of grass covered 
by night and uncovered by day soon changed to a yellowish colour, and 
looked sickly, and apparently dying." 
This fact shows that there is something connected with the influence 
of light, or some rays with which we are unacquainted, radiating from 
the sun, or some intercepted influence from the ground or other sources 
unknown to us, which powerfully influence vegetable life. Light has 
not only been generally said to be essentially necessary to vegetation, 
the green colour depending upon it, but the more of it the better : 
here, however, seems to be an experiment showing that this is not the 
case, and that (if it be light) the small and seemingly feeble rays re- 
flected or dispersed from the clouds at night are sufficiently active and 
powerful. Possibly some radiation from the surface to the skies, of 
which we have no knowledge, intercepted by the physical interference 
of fibrous covering, may alone occasion its modus operandi. To those 
who are disposed to go into the philosophy of this subject I would 
observe, that in the case of the experiment of the fibrous covering being 
placed two feet above the growing "grass, there could be no interception 
of the direct rays of the sun on that part lying perpendicularly below 
the south side of the supporting frames ; yet there was no visible differ- 
ence either in the colour or growth of the grass lying beneath the east, 
west, north, or south sides of the frames. 
The practical instructions for the use of fibrous covering are few, but 
essential to profitable results. Straw of wheat, oats, or rushes is to be 
VOL. VII. U 
