CHLOROSPEKME.E. 189 



filled. This matter, when mature, becomes granular, and is 

 converted into those active spores (or zoospores) whose ani- 

 mal motions I have already mentioned ; and which are pro- 

 bably analogous to the gemmae or buds, by which more per- 

 fect plants are propagated. This, at least, is the opinion of 

 Mr, Ralf's, one of the most accurate observers of these 

 minute plants. 



The frond in others, a little more advanced in organization, 

 consists of several cells strung together in filaments, such as 

 we find in Conferva and its allies. These filaments are 

 either simple or branched, and are increased, either by 

 additional cells continually added to the growing apices, and 

 as it were budding out of the old cell ; or else by the bi- 

 partition of the first-formed cells. In the first case, a little 

 bud-like body is formed at the apex of an old cell, which 

 lengthens and widens until it attains the dimensions proper 

 to the species ; when it stops, and gives birth to a bud 

 of like character. In the second case, a transverse separa- 

 tion takes place in the middle of the endochrome of an old 

 cell ; a partition or dissepiment is gradually formed, and at 

 last, two cells result from what had been one, and lengthen 

 till they attain their normal state, when each is again capable 

 of this fissiparous division. Such appears to be the mode of 

 growth in Conferva melago7iium, (Brea, Sac. ; while most of 

 the Cladopliora; grow by budding. The difference, however, 

 is more apparent than real, for a fissiparous division takes 

 place in both cases. The Conferva3 are commonly propa- 

 gated by zoospores; but sometimes form sporangia, elaho- 

 rated in their cells. From the filamentous Confervce the 

 passage is easy into the Batrachospermaceae, where a com- 

 pound frond is built up by the union in bundles and whorls 

 of a number of filaments ; and also, through Anadyoinene, 

 into the Siphonaceae and Ulvaceae, where the frond assumes a 

 multitude of forms, expanding into membranes or contracting 

 into hollow tubes. In some of the highest members of 

 the sub-class, as in the Caulerpacese, there is an obvious dis- 

 tinction of organs into root, stem and leafy appendages ; but 

 even in these, high in structure as they appear, no distinct 

 conceptacles of fruit have yet been observed. 



The Chlorosperms are more widely diffused than any 

 other Algae. A comparatively small number are found in 

 the waters of the sea.' A far larger proportion inhabit fresh- 

 water rivers, lakes and ponds, ditches, bog-holes, the gutters 

 of houses and sewers ; — in fact, anywhere that fresh or 



