SAPROPHYTES AND THEIR RELATION TO DECAYING BODIES. 99 



water flows down to this place it is stemmed by the membrane, as by a dam, and 

 diverted right and left into the two grooves. In this way water is prevented 

 from accumulating between the leaf-sheath and haulm, where it might do damage. 

 In many reeds the contrivances for irrigation are even more complete than this. 

 Sometimes hairs depend from the margin of the membrane in the direction of the 

 grooves and, like a wick, lead the water in the proper direction. 



An opportunity will occur later on of showing how the conduction of rain to 

 particular sjjots has an important bearing on the phenomenon of absorjDtion by 

 aerial parts of plants: and also in the regulation of transpiration; and how, by 

 means of the apparatus for water-irrigation, not only absorptive cells at the 

 extremities of roots in the earth, but special organs on the foliage-leaves as well, 

 are often supplied with water. 



3. ABSORPTION OF ORGANIC MATTER FROM DECAYING 

 PLANTS AND ANIMALS. 



Saprophytes and their relation to decaying bodies.— Saprophytes in water, on the bark of trees, and 

 on rocks. — Saprophytes in the humus of woods, meadows, and moors. — Special relations between 

 Saprophytes and the nutrient substratum, — Plants with traps or pitfalls for animals. — Insecti- 

 vorous plants which perform movements for the capture of prey. — Insectivorous plants with 

 adhesive apparatus. 



SAPEOPHYTES AND THEIR EELATION TO DECAYING BODIES. 



Whenever plants which take up organic compounds formed in the process of 

 decay are the subject of discussion, the first examples that occur to everyone are 

 members of the great family of Fungi, specimens of which make their appearance 

 wherever dead animals or plants ai-e undergoing decomposition. We recall the 

 moulds, Plasmodia, puff-balls, and mushrooms, which grow from dead organic bodies, 

 and are associated with the unpleasant mouldy and cadaverous smell always 

 perceptible in their neighbourhood. 



Many of these organisms do, in fact, belong to the class of Saprophytes. Indeed, 

 one group of them is itself the cause of the chemical decomposition of dead plants 

 and animals called decay. Their elongated thin-walled cells, the so-called "hyphaj", 

 thread themselves through dead bodies, and unite to form strands, bundles, net- 

 works, and membranes, the whole constituting a structure to which the term 

 "mycelium" is applied. These mycelia are often to be seen, with the naked eye, 

 covering large areas. For instance, in damp cellars, mines, and railway-tunnels, any 

 old rotten wood-work is clothed with delicate, whitish reticula and membranes. 

 The heaps of grape-skins, stalks, and other refuse piled up in the open air by the 

 side of vineyards after a vintage, are usually so completely overgrown by mycelia 



