344 THE SEA SHORE 



influence of light, the plant is enabled to decompose the carbonic acid 

 gas of the atmosphere, using the carbon for the purpose of building 

 up its own substance, and setting free the oxygen into the air again. 

 Others contain no chlorophyll ; and these, having no power of feed- 

 ing on carbonic acid gas, are more or less dependent on organic 

 matter for their supplies of carbon. 



Only very slightly removed from these minute plants are the- 

 Algce of fresh and salt water, varying in size from microscopic 

 dimensions to enormous plants, the lengths of which may reach 

 many yards and the weight several stone. They contain chloro- 

 phyll, and can therefore avail themselves of inorganic food material ; 

 and although some multiply only by repeated subdivision of their 

 cells, others develop sexual organs by the union of which fertilised 

 spores are formed. The nature of these Algae will be more fully 

 described presently ; and we will go no further now than to justify 

 the location of such large and conspicuous plants (as many are) so 

 low in the scale of vegetable life by stating that they are entirely 

 cellular in structure, never producing true vessels such as we see 

 in higher plants ; and that though some of them develop parts 

 which more or less resemble the leaves and roots of higher forms, 

 the former are far more simple in structure and function than true 

 leaves and the latter are never engaged in the absorption of food 

 from the soil to which they are fixed. 



Another important group of the Thallophytes is formed by the 

 Fungi, which include the familiar mushrooms, toadstools, and the 

 sap-balls so commonly seen on decaying trees ; also the smaller 

 forms known as moulds, mildew, and smut. These, also, are en- 

 tirely cellular in structure ; and, since they develop no chlorophyll, 

 are compelled to live as parasites on living beings or to derive their 

 food from decaying organic matter. Thus they are the creatures 

 of corruption, their presence always denoting the breaking down 

 of living matter or of matter that has previously lived. 



Now leaving the TJiallophytes, and passing over the small 

 group of aquatic plants known as the Charales, we come to the 

 Muscinece, which contains the Liverworts (Hepaticce) and the Mosses 

 (Musci) . 



The plants of both these groups require much moisture, and are 

 found principally in damp, shady situations. Like the preceding 

 groups they are cellular in structure, never producing true vascular 

 bundles such as the higher plants possess ; and their life histories 

 are rendered interesting by the ' alternation of generations ' which 



