RELATIONS OF SAPROPHYTES TO THEIR NUTRIENT SUBSTRATUM. 113 



alpina, Carex curvula, Juncus trifidus), various anemones, campions, umbelliferous 

 plants, violets and campanulas (e.g. Anemone alpina, Silene Pumilio, Meum 

 Mutellina t Viola alpina, Campanula alpina) and several mosses (e.g. Dicranum 

 elongatum and Polytrichum strictum) 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 Primulaceae and Gentianeae (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. Lycopodium inundatum, JSriophorum vagin- 

 atum, Trientalis Europcea) 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 graphitic 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 EELATIONS OF SAPKOPHYTES TO THEIR NUTEIENT 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 Euglense, 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 algae 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 

 VOL I. 8 



