EXPERIMENTS ON SOME SPECIES OF FERNS. 159 
prismatic spectrum; but in some cases this action is positive, exciting; in 
others negative, depressing. 
5. The most luminous rays are proved to prevent all chemical change upon 
inorganic bodies exposed, at the same time, to the influence of the chemical 
rays. 
6. Hence actinism, regarded at present merely as a phenomenon differ- 
ent from light, stands in direct antagonism to light. 
7. Heat radiations produce chemical change in virtue of some combined 
action not yet understood. 
8. Actinism is necessary for the healthful germination of seed; light is 
required to excite the plant to decompose carbonic acid; caloric is required 
in developing and carrying out the réproductive functions of the plant. 
9. Phosphorescence is due to actinism, and not to light. 
10. Electrical phenomena are quickened by actinism, and retarded by light. 
Numerous other points‘of minor importance will present themselves on 
studying the facts described. Without venturing to obtrude my own views, 
I now leave the subject for that full investigation which it will, I trust, re- 
ceive, as promising beyond all others to enlighten us on those curious phz- 
nomena which appear to link together the organic and the inorganic worlds. 
Dr. Dauseny reported that some little progress had been made by him 
during the present season in the inquiry which was commenced last year, as 
stated in the Reports of the British Association, vol. xviii. p. 56. The object 
he last had in view was to ascertain whether such an addition to the amount 
of carbonic acid in common air, as that which had been shown by the ex- 
periments of the preceding year to be compatible with the health of ferns, 
would tend to promote their growth and luxuriance in a greater degree, than 
the proportion of the gas normally contained in the atmosphere did under 
similar circumstances. 
He therefore had placed three species of ferns, viz. Péeris longifolia, 
Pteris serrulata and Nephrodium molle, under a jar, the air of which was 
impregnated with about five per cent. of carbonic acid gas, which amount was 
kept up by occasional additions throughont the whole period during which 
the experiments were continued; whilst three other ferns of the same kinds 
were kept under a similar jar containing common air without any such 
addition, 
After the expiration of eleven weeks the two sets of ferns presented in 
their general aspect no material difference, although whatever superiority 
there might be, appeared to be on the side of the plants which had grown 
in air containing only the normal amount of carbonic acid. 
In another set of experiments, however, in which two similar sets of ferns 
were watered, the one with rain water, the other with water impregnated 
with carbonic acid gas, those under the latter treatment appeared, after a 
time, decidedly more vigorous than the former. 
