Watson. — Sphagna: Habitats , Adaptations , and Associates. 551 
spores are shed when the plant is exposed to drier conditions than usual, 
and this may account for the papillosity of the spores (Fig. 3, m). 
Associates. 
The associates of Sphagnum will be dealt with in a later paper. 
General Conclusions. 
Sphagna obtain their mineral salts from very dilute solutions. 
They possess a special method of obtaining mineral food by adsorbing 
the base and liberating the acid. 
In order to do this, special devices (which may seem of a xerophytic 
nature) are adopted to obtain a sufficient quantity of dilute solution, and to 
get rid of the superfluous acid and water. 
These devices vary in different groups of Sphagnum. During periods 
of drought the income of exposed plants is suspended and the xerophytic 
devices may act as such, keeping the plant in a moist condition till a further 
supply of dilute solution is available. 
