CALLITHAMNIOX. 193 



filaments near the walls of the cavity, and they are the 

 parent cells of the germ cells, which produce the spores or 

 seeds. Each of these sporangia gives forth a cluster of 

 eight cells, and are therefore also called octospores. 



In the hermaphrodite fuci the spores do not leave the 

 receptacle until after their fecundation ; but in Fucus vesi- 

 culosus, which is a dio3cious plant, the antherozoides meet 

 the spores in the water directly after they issue from the 

 receptacle. 



To observe this, take an olive-green receptacle, which is 

 the female, and set free a few spores in a drop of sea-water 

 in a shallow cell ; then liberate a few ripe filaments from 

 an orange-yellow receptacle, which will contain the anthe- 

 rozoides, and the whole process of fertilisation may be 

 watched with a power of 250 diameters. 



Then, if you further wish to prove the subsequent pro- 

 cess of germination, a little care and patience will enable 

 these very spores to grow from the cell of what is called a 

 "growing slide/' or even in a tumbler of water, taking 

 precautions to keep the water fresh and still, by drawing it 

 off with a siphon, and renewing it daily in the same gentle 

 way. 



The fructification of the Rhodospermese, or red Sea- 

 weeds, has not yet been so thoroughly investigated, and 

 the varied forms of the spore-cases will be the chief beauty 

 as well as value of the following preparations. 



CALLITHAMN1ON. 



There are twenty-five species of this plant, and most of 

 them are common on the shores of Great Britain ; its name 

 is derived from two Greek words, signifying "beautiful 

 little shrub," and it is very beautiful, with a rosy or brown- 

 ish-red frond, or rather filament, jointed and branching, 

 bearing two kinds of fructification : 



1, External tetraspores seated upon the branches. 



2, Roundish or lobed berry-like receptacles, called 

 favelke, seated on the main branches, and containing many 

 spores. 



Callithamnion delights in mud- covered rocks. C. roseum 



13 



