INFLUENCE OF SOLAR RAYS ON THE GBOWTll OF PLANTS. 21 
The trough of sulphate of copper obstructed more lieat but admitted the 
passage of a larger quantity of light. It gave on examination, light GO. 
heat 54, and actinism 93 parts. 
The solution of ammoniate of copper was of so deep a colour that only 25 
parts of light passed it, and 48 of heat, whilst from 93 to 95 of actinism 
escaped any absorption. 
Common cress {Lepidium s<tlivxm\ Mignionetto {Utseda adorntu), 7Vri- 
week Stocks {Mafhiola incana) and Minor Convolvulus, were placed on the 
moKt flannel, and the tested gla» frame being placed over the andurkenod 
halt, the box was exposed to sunshine in a warm room. The cress under 
the actinic influence exhibit<nl signs of germination witliio twenty-four hours, 
hut no change was obsc-rvutile beyond a swelling of the seed from the 
absorpuon of water over that jiortion in darkness: on the second day all the 
cress bad germinated over tJie exposed part*, uml the other seeds were apria- 
rently m a forward condition, whereas in the dark, with the exception of th»- 
cress m which germination was established, but little ulti-ratiou was seen in 
the other seeds. Although the periods of germination ditfered in each va¬ 
riety of these seeds, under the conditions to which they were f-xiH>«>d, vet in 
every mstonce the seeds influenced by actinic radiations germinated in one 
hall the tune ot those seeds placed in the dark. 
The experiment was repeated, the seeds being placed in earth instead of 
on moist flannel. In everv experiment the seed germinated in much less 
UDie under the influence ot tlie actinic rays than in the dark. 
Several ^rangements were made for tho purpose of ascerfaming if the in- 
Huence ol the chemical rays was confined to the surface of tho soil, or if they 
.t! ^ * obtained the most satisfactory evi- 
dei.ee, that under the influence of tho rays which passed the blue glasses, 
germination was set uj. at a depth below the surface, at which under tlie or- 
d. lary conditions it did not toko plao.e. The coromoii cress, placed an inch 
below a somewhat clayey soil, germinated with difficulty under the ordinary 
tinn * of the actinic radiations was such that germina¬ 
tion was but slightly retarded. Various other seeds were tried, as. 
Groundsel. Senceio v uigarifl. 
Convolvulus . Convolvulus minor. 
Vetches. Vicia sativa. 
. ... Avena sativa. 
len-wcek Stocks. Mathioln annua. 
Mignioiiette . Reseda odonvta. 
germination was get up by the agency of the radiations, 
thp 2-f«n a less time, and at a greater depth in 
Hio f iV- comparative exjicriments in which the seed was exposed to 
u influence of light and its associated radiations as combined in the or¬ 
dinal solar beam. 
^ bcD a solution of sulphate of copper was employed, admitting, a* we have 
glasses, tho evidences of the acceleration of gemii- 
were not so great. These experinicnts were however very satisfactory, 
‘■fPdlate with considfrable nicety tho relative propor- 
inu-; ^ ^ f aetiuism, they aftbrded the means of ascertaining the retard- 
IfUor cence of the luminous power. After a great number of experiments, 
inr.p crtdeiif, that as the relative quantity of the luminous priodple was 
"ds the iuflueaco of the chemical radiations diminished. In 
triAfFi, ^ ®'"cjoniate of copper, as stated, the germinatioti of all the seeds 
came more rapid ; and that this was pot the mere influence of shading 
