38 



The Naturalist. 



incrustcd with carbonate of lime. The stems and branches are made 

 up of tubules, in which the circulation of the cell contents is plainly 

 visible under the microscope. The reproductiye organs arise at the 

 junction of the branchlets with the branches, and are of two kinds, 

 called granules and nucules. The granule, or male organ, is a small 

 bright orange body ; it has two coats, the outer is transparent, the 

 inner is orange red, and made up of eight three-cornered plates, 

 composed of triangular cells. These cells project at the edges, 

 forming indentations, by which the plates are locked together, like 

 the bones of the skull ; when ripe, however, they burst open. From 

 the centre of each plate a tube projects internally, these in the centre 

 of the granule meet together and are connected with each other and 

 with another pillar, which is a continuation inwards of the short 

 stalk by which the granule is attached to the branch. From this 

 point of union spring a number of long wavy, closely-jointed threads, 

 each joint being a cell in which is developed a moving filament like 

 those of mosses. The nucule is an oval body made up of a mass of 

 cells, and coated with five spirally-twisted tubes, the points of which 

 project at the top of the nucule like a crown ; in the centre between 

 them is a minute opening by which the fertilizing particles are 

 supposed to gain access to the interior. The nucule, when ripe, falls 

 off and germinates, producing a prothallus, from which several young 

 plants arise by budding. Thus countless thousands of fertilizing 

 filaments are produced for each nucule to be impregnated ; we meet, 

 however, with a similar disproportion between the number of pollen 

 grains and ovules in some flowering plants, especially those fertilized 

 by the wind, as the hazel and the yew. 



Having thus given a brief description of the flowerless plants, I 

 now come to the second part of my paper, viz., their " habitats," — i.e., 

 the places in which they grow. The geographical distribution of the 

 cryptogams has been but imperfectly worked out, but is a field full of 

 promise to the student of geographical botany. These plants are far 

 less liable than the flowering plants to be introduced or exterminated 

 by direct human agency ; the influence of man upon the cryptogamic 

 vegetation is indirect in providing or removing the conditions of soil, 

 atmosphere, and moisture suitable to their growth. The following 

 remarks will have reference especially to the perennial mosses liver- 

 worts and lichens ; the other orders for the most part either follow 

 the same general laws, or depend for their occurrence rather upon the 

 presence of the particular soil required by them, than upon climatic 

 conditions or geographical situation. 



(To be continued.) 



