4 
THE PLANT WORLD. 
chapter. Here I will only say regarding absorbing-mechanism, 
that whilst adaptations to absorption by the root-surface and by 
root-hairs are generally accepted phenomena, insufficient recogni¬ 
tion has been given to the part played by fungus-mycelium in 
symbiotic mycorrhiza. Its adjuvant character in feeding has 
been long advocated, although there are those who^ hold that the 
condition is purely pathological. I conclude, however, from ob¬ 
servations on cultivated plants, that the cooperation of fungus- 
mycelium and root is not a feature of only certain species as is 
supposed, but is possible to all rooting plants as an efficient method 
of water-absorption and is operative where conditions serve. It 
is never absent from spermophytous plants of all kinds growing 
with their roots confined in tubs when the roots reach and pene¬ 
trate the wood of the tub beginning to decay. Then the adapta¬ 
tions to first-transmission of absorbed water are variable and no 
less important, taking the form, in conditions of physiological 
drought, of modification of the general cortical cells to facilitate 
passage of water, but more specially of the development of exo- 
dermal transfusion-cells, which are not merely a feature of soil- 
roots in some few saprophytes, but a widely distributed and 
characteristic xerophilous construction. 
Interpretation of Gardeners' Riddles .—From the many riddles 
that confront the gardener to which the foregoing data offer a 
key I adduce the following as illustrations: 
Marsh-plants Growing in Sand. —Plants which in nature in¬ 
habit marshy stations (indicated often in their specific name, e. g.. 
Ledum palustre, Scirpus palustris ) thrive in dry sandy garden-soil 
—from the horticultural standpoint (if flower be the aim) may 
be said to do better there, for if leafage is less, flowering is more 
profuse than in the natural station. No apparent cultural para¬ 
dox is more striking than this. Applying the principle of physio¬ 
logical drought the explanation is clear: physically different, the 
soil-environment in the two situations is physiologically the same 
—dry to the plants. The botanically-informed gardener could 
surmise this from the xerophilous character of the plants. 
Epiphytic Orchids in Pots. —Similarly, to the gardener’s ques¬ 
tion : what resemblance can there be between a flower-pot filled 
