374 
REPORT—1854. 
chemical rays freely: it may also be considered as interfering much with the 
transmission of heat. The red glass, on the contrary, freely admits the calo¬ 
rific influence, but stops the chemical, whilst, like the blue, it diminishes 
greatly the luminous. The yellow again scarcely decreases the illuminating 
power of light, but almost destroys its chemical action.” 
The series of experiments on hyacinths, which was described in the last 
Report, was repeated with additional attention to the effects of partial or 
complete darkness. The Inrge colourless, blue, red, and yellow bell-glasses 
were employed, together with a partially obscured colourless shade, and a 
partially obscured yellow shade; and another experiment was instituted 
under a glass shade placed in u large box, so that the light was completely 
excluded, except when for a few moments the lid might be removed for the 
purpose of observing the progress of the experiment. As in the preceding 
experiment, the bulbs were all of the same description, of a healthy appearance, 
and of about the same size. After being weighed, they were placed asbefim 
on the top of colourless glasses, filled with pure water, and covered with tnr 
large bell-jars. In this case the jars were themselves placed upon the p' f - 
forated boards, with the arrangement of tarlatane, &c., mentioned in the 
previous paper. The experiments were commenced on December I 
each of them was successful ; the results accorded in some points with tlio* 
of the former occasion, but in other respects there was considerable dis¬ 
crepancy. The experiments made in partial or complete obscurity were pr- 
haps the most instructive. n 
Rootlets begun to appear immediately under the dark shade, ant on ur- 
cernber 26th, that Is, after sixteen days, they were found to be 1 | W 
length. They grew rapidly, and were very numerous. They were U 
long, and appeared to have little strength. Under the obscured colour _ 
and obscured yellow glasses, the rootlets also began to grow W- ^ 
commg three-quarters of an inch long in a fortnight’s time; whi'etad^ 
bine and colourless glass exposed to the full power of the light, th 
d,t notso qutoMy attain any length, and in the same space of 
was scarcely anything observable under the red or yellow glass* , v 
continued to grow under the obscured glasses until the bcgtawjg «' 
bruary, but they arrived more rapidly at maturity under the influfi ' vC „ri- 
white am blue light. Under the red shade the roots never a W 
siderable length, but they were stout and strong. Under the yellow had ^ 
was scarcely any growth below the bulb until near the end ofJanuary, 
° nS o 9tl ' ag r ,,g roots maUp their appearance. This is ^‘So-vl 
hv ti 16 1 eCt , liat was observed during the previous season to P ^ 
by the coloured glasses. This shows that the development of ^*V uf jtT 
■, , e n l ost l * n the absence of all solar radiations; tlrnt P n ' , ., er i»! 
S also favouralde; that the less refrangible rays of the 
power to re ard their growth, and that the luminous and calor^ . 
peculiar actions of their own. . anv0 fti* 
As to the haves, little appearance of growth was observable m ■. 
hyacinths till December 4 P th, when tlfose under the cdou*^^ 
those .,n? an . t0 shoot; thHt u «*der the red glass followed very ^ 
ZZZSr.P.’f" aml tUe Partially and wholly obscured ifgfa 
11 ’ f-° , ° r about tliree weeks (oncer. The leaves grew most r.| U ert |,r 
varfous him 1 1,0 comparisons of the length of the lca ^j, „» ,bf 
ia^ZdSS^v? WneC9 be interesting. They. 
not one of ff " hen all the plants were m v 'S or0 “; c p | a n^ ^ 
attained ££% ^ «” d ' ^ “* P 
