vi.] STONE WOR TS. 4 7 



ruination of the spore of a fern below). The hypha-like 

 tube elongates, and becomes divided, transversely into cells, 

 the protoplasm of which developes chlorophyll. Very soon, 

 the further growth of this pro-embryo is arrested. But one 

 of the cells, which lies at some distance below the free end 

 of the pro-embryo, undergoes budding, and gives rise to a 

 set of leaves (which are not arranged in a whorl), amidst 

 which a bud appears, which has the structure of the termi- 

 nal bud of the adult Cham stem, and grows up into a new 

 Chara. 



We have then, in Chara, a plant which is acrogenous (or 

 grows at its summit), and which becomes segmented by the 

 development of appendages, at intervals, along an axis; 

 which multiplies, asexually by bulb-like buds, and also mul- 

 tiplies sexually by means of the antherozooids (male ele- 

 ments) and central cells of the sporangia (female elements); 

 in which the first product of the germination of the impreg- 

 nated ovicell is a hypha-like body, from which the young 

 Chara is developed by the germination and growth of one 

 cell; so that there is a sort of alternation of generations, 

 though the alternating forms are not absolutely distinct 

 from one another. 



Chara flourishes in pond-water under the influence of 

 sunlight, and by the aid of its chlorophyll, so that its nutri- 

 tive processes must be the same as those of Protococcus. 

 From its complete immersion, and the absence of any duct- 

 like, or vascular tissues, it is probable that all parts absorb 

 and assimilate the nutriment contained in the water; and 

 that, except so far as the reproductive organs are concerned, 

 there is a morphological differentiation of organs, unaccom- 

 panied by a corresponding physiological differentiation. 



Nitella is a rarer plant than Chara, and is simpler in 

 structure, its axis being devoid of the cortical layer. In 



