242 REPORT—1852. 
entered. No secondary leaves ever appeared, but each plant consisted of 
two long white leaves of about 9 inches in length, so thin and flaccid that 
they were unable to support themselves; and after thirty days they drooped 
entirely and became mouldy. The corn-plants under the other glasses grew 
more slowly, but put forth many leaves, attained a height of 10 or 12 inches, 
and remained healthy throughout the winter and spring. Those under the- 
yellow glass were the most sturdy in their growth; and those under the blue 
alone appeared thin and unhealthy. 
Mallow-seeds (Malope trifida) were sown in garden mould, and placed 
under the various glasses near the commencement of September, the arrange- 
ments being the same as in the preceding experiment. They began to grow 
after the lapse of a few weeks, first under the colourless glass, then under the 
blue, and afterwards under the red, yellow, and darkened glasses at about 
the same time, October 8th. Thin etiolated stalks, with only the first pair 
of leaves, and those badly developed, about 2 inches in length, were all that 
was produced under the darkened shade. In about a fortnight they died ; 
and in the middle of March some other seeds sprouted in a precisely similar 
manner. The mallows under the other glasses grew more healthily and sur- 
vived much longer, but in no instance did they arrive at maturity: the best 
plant was one that grew under the yellow light; it had sprouted in the early 
part of January and put forth many leaves, reaching the height of 5 inches. 
They grew worst perhaps under the blue glass. A self-sown Stellaria grew 
luxuriantly along with the mallows under the red, and a grass-plant under 
the yellow shade. 
In a paper read by my brother and myself before the Association last year, 
and published in the Philosophical Magazine for September 1851, we re- 
marked that plants kept in an unchanged atmosphere appear to enter into a 
sort of lethargic condition. An experiment was instituted for the purpose 
of ascertaining whether the alteration in light produced by coloured media 
made any marked variation in this matter; and as the pansy and Poa annua 
were the plants generally experimented on in our previous investigation, 
they were employed here likewise. Six pansies newly struck, which had 
taken good root and were vigorous, were planted in six flower-pots contain- 
ing good garden mould; and with each was also placed a grass-plant in 
flower. They were all set in trays filled with water to the depth of an inch, 
or thereabouts ; five were covered with the different descriptions of glass 
shades dipping into the water, so as to cut off all communication between 
the external and internal atmospheres; while one was freely exposed to all 
the changes of the surrounding air. The experiment was commenced on 
October 17th, and access of air was never permitted to the covered plants. 
The results under the glasses were very various, but how far they depended 
upon the character of the light or upon the peculiar atmospheric condition, 
could not be determined with any accuracy. One thing however was clear, 
that the plants survived much longer for being in an unchanged atmosphere. 
The pansy that was not covered by any shade was attacked with aphides 
eight weeks after the commencement of the experiment, and although these 
were washed off, it drooped before the end of December. The Poa also 
scarcely survived the winter. Under the colourless glass the plants remained 
healthy much longer ; the pansy was attacked by the forementioned insects 
at the commencement of December, but although it was necessarily impos- 
sible to remove the aphides without disarranging the experiment, the plant 
lived till March. The grass-plant grew very luxuriantly. A curious phe- 
nomenon was observed. As the air within the glass shade was perfectly still, 
the ripe seeds of the Poa did not fall from the flower-stalk, and through the 

