AS A FUNCTION OF LIVING PROTOPLASM. 301 
similar range of temperatures. The inference is, that living proto- 
plasm has a power of controlling and regulating the loss of water 
which a dead organic structure does not possess. 
CONCLUSIONS. 
The general conclusions which the above-described experi- 
ments seem to warrant are, that plants, such as Mushrooms, which 
do not possess chlorophyll at all, transpire more under light 
than in darkness, but exhibit slight, but not very appreciable, 
differences under light of various colours. Transpiration, how- 
ever, appears to be more sensitive to increments of temperature 
than to colours, and perhaps than to pure white light itself. 
Etiolated plants, as Seakale, which under normal conditions 
would be green, still show some slight difference, due to coloured 
rays, such as are, however, much more pronounced with plants 
possessing chlorophyll. 
In both cases transpiration is a function of living colourless 
protoplasm ; this function, however, being greatly enhanced by 
the presence of chlorophyll, in consequence of the power possessed 
by the latter substance of absorbing certain rays, which then, by 
their conversion into heat, raise the temperature within the leaf 
and thereby increase the loss of the vapour of water. 
Lastly, the difference in the effects of transpiration from a 
living organism and evaporation from a dead one can easily be 
seen in the usually relatively greater amount of water lost under 
the latter process under similar conditions and in the same space 
of time. A further difference will be noted hereafter; and the 
rcader may be referred to M. Masure's paper, mentioned above, 
for other differences. 
Since this paper was written a short communication from 
M. Ph. van Tieghem * has appeared, in which he also suggests 
that the term transpiration should be given to the vaporization 
of water from protoplasm, and which occurs independently of 
chlorophyll. This, he remarks, is a process common to animals as 
well as vegetables, or to all living beings :—“ Elle croît, comme on 
sait, avec la température, avec la sécheresse et Pagitation de l'air. 
La lumière aussi s'accélére; au soleil, un organe sans ehlorophylle, 
un pétale de Mauve ou de Lis, par example, transpire jusqu'à 
deux et trois fois plus fortement qu'à l'obscurité.” 
* Bull. de la Soc. Bot. de France, 1886, p. 152. 
