AS A FUNCTION OF LIVING PROTOPLASM. 295 
This may appear strange with regard to evaporation, but it is a 
well-known fact that dark bodies especially, such as a dead 
mushroom, can absorb radiant energy and convert it into heat. 
This is well illustrated by small objects, such as dead leaves, 
pieces of bark, small stones, dead insects, &c., which when lying on 
ice gradually sink into it, sometimes to a depth of several inches. 
This is frequently observable on the glaciers of Switzerland, and 
that, too, when the temperature of the air in contact with the 
ice must be close upon the freezing-point of water. 
That a mushroom with blackened gills absorbs much light is 
further proved by making an alcoholic solution. If this be 
examined with a spectroscope, it will be found that the only 
light which is transmitted is a very dull red and green, showing 
how much of the spectrum is arrested. 
There is another point illustrated in the above experiments, 
namely, that a living organism transpires ceteris paribus less than 
when dying or dead, i. e. when it is replaced by evaporation. 
Thus specimen No. II. will be seen to have transpired more 
largely from Jan. 5 to 7 (indicated by * p. 289), when decay had 
set in, though there was no special rise of temperature to account 
for it. It was also more pronounced by day than at night. 
Similarly, specimen No. IV. was beginning to dry up about 
Jan. 31 (* p. 290). From that-date to the 3rd, the loss per hour 
was markedly greater than it had been previously. 
EXPERIMENTS WITH ETIOLATED SEAKALE. 
The following experiments were made with plants of Seakale 
which had at first been grown in a dark cellar. One had a rhizome 
3 inches in length, and foliage consisting of white petioles with 
purplish arrested blades. The other had a rhizome about 5 inches 
in length, with long petioles varying from 6 to 12 inches in 
length. The rhizomes, with a few rootlets attached, were 
wrapped up in saturated cotton-wool, and the whole enveloped 
in guttapercha sheeting, so that no moisture could possibly 
escape except from the exposed petioles. The plants were 
subjected to light transmitted through coloured glasses suc- 
cessively by day, and placed in total darkness a night. They 
were carefully weighed every morning and evening, and the 
losses by day and by night reduced to losses per hour for each 
Pd respectively, as in the case of the Mushrooms described 
above, 
