RELATIONS OF SAPROPHYTES TO THEIR NUTRIENT SUBSTRATUM. 113 
alpina, Carex curvula, Juncus trifidus), various anemones, campions, umbelliferous 
plants, violets and campanulas (eg. Anemone alpina, Silene Pumilio, Mewm 
Mutellina, Viola alpina, Campanula alpina) and several mosses (e.g. Dieranum 
elongatum and Polytrichum strietwm) which clothe the humus on stretches of turf 
and in inclosures. 
Many of the plants also that are native on the black graphitic soil in hollows 
of high mountain ridges take up organic food from their substratum. These 
include Meesia alpina and various other mosses produced exclusively in places of 
the kind; and, above all, numerous Primulacez and Gentianex (Primula glutinosa, 
Soldanella pusilla, Gentiana Bavarica). It seems, moreover, to be by no means a 
matter of indifference to these plants at what temperature, and in what state of the 
air, in respect of moisture, the decomposition of humus takes place. If species which 
grow abundantly in these localities are dug up and transferred, together with the 
black earth in which their roots are imbedded, into a garden, and are there 
cultivated in such a way that the external conditions are as nearly as possible those 
of the original habitat; or if young plants are reared from seed in the same black 
humus-filled earth, they thrive only for a short time, soon begin to fade, and within 
the space of a year are dead; whereas, alpine plants belonging to the same altitude 
above the sea, but rooted in loamy or sandy earth, flourish excellently in gardens 
as well. Various moor-plants (e.g. Lycopodiwm inundatum, Eriophorum vagin- 
atum, Trientalis Ewropea) only live a short time in a garden even though the 
clods of peat, in which their roots are imbedded, are transplanted with them. This 
fact can scarcely be explained except by supposing that the organic compounds, 
produced by the decay of vegetable remains on alpine heights and moors, are 
essentially different from those evolved by similar matter under the changed 
conditions of temperature and moisture occurring in a garden at a lower level. 
Gardeners say that the peat and black graphitie soil from the slopes of snowy 
mountains turn sour in gardens, and they may be to this extent right, that in all 
probability the humic acids produced under altered circumstances are different. 
SPECIAL RELATIONS OF SAPROPHYTES TO THEIR NUTRIENT SUBSTRATUM. 
In the plants under discussion, the cells which absorb organic compounds are, 
taken all in all, very similar to those which absorb mineral food-salts. Where there 
is no cell-membrane, as in the case of Plasmodia and Euglenz, the food diffuses 
through the so-called ectoplasm, or outer layer of the protoplasm, into the interior of 
the cell. Saprophytic marine and fresh-water alg® are able to absorb the products 
of decay in the water around by means of their superficial layers of cells. The 
mycelia of fungi have the power of taking in nourishment with special rapidity. 
Each hypha, or more accurately, each long, delicate-walled cell of a mycelium is, to 
a certain extent, an absorptive cell; its entire surface is capable of exercising the 
function of suction and of withdrawing from the environment, along with water, 
the very substances which are needed. The coral-like underground stem of 
Vor. I. 8 
