THALLOPHYTA 



33 



single cells of the surface. In the Fungi the differentiation into 

 antherozoids, with one doubtful exception, does not take place, 

 and the male organ is only a swollen cell or branch of a hypha, 

 containing usually undifferentiated protoplasm. In most cases 

 the antherozoids are ciliated and consequently motile ; in certain 

 groups of both Algae and Fungi they are non -motile. In this 

 case the}' become sooner or later clothed with a cell-wall. 



The female organ is usually- an oogonium {fig. 782) consist- 

 ing of a single cell, often carried on a stalk, and containing one 

 or more oosjjJiercs. In other forms it is an archicarj} {fig. 783) 



e-r>' 



FiCx. 784 



I — gp. 



F.J. 783. Section of thallus of a licben, show- 

 ing arclucarps, e,/. Fig. 78i. Procarp of 



one of the Red Seaweeds, tr. Trichogyne. 

 sp. Sperinatia. After Kny. 



or procariyium {fig. 784) and does not contain any differentiated 

 oosphere. 



The Thallophyta are divided into three classes, the Algae, 

 Fungi, and Lichens. The first contain chlorophyll, the second 

 do not. As a consequence their habit of life is essentially dif- 

 ferent ; the former can prepare food for themselves from the 

 constituents of the air and the medium in or on which they live ; 

 the latter are compelled to obtain them directly or indirectly 

 from other organisms. The members of the third class are 

 partly algal and partly fungal. 



VOL. II. 



