574 MICROSCOPIC FORMS OF VEGETABLE LIFE -THALLOPHYTES 



shaped processes (fig. 432, B). As in many preceding cases, these 

 plants multiply themselves by the conversion of the endochrome of 

 certain of their cells into zobspores, and these, when set free, are 

 seen to be furnished with either two or four cilia. * Resting- 

 spores' have also been seen in many species. One of the most 

 beautiful objects under the microscope is Draparnaldia glomerata, 

 not uncommon in still water. It consists of an axis composed of a 

 single row of large transparent cells containing but a small quantity 

 of chlorophyll. From this proceed at regular intervals whorls of 

 slender branches, the endochrome of which is deep green, and every 

 branch ends in a delicate hyaline hair of extraordinary length. The 

 mode of reproduction of the Chcetophoracece closely resembles that of 

 the Gonfervacece. 



The Batrachospermese, whose name is indicative of the strong 

 resemblance which their beaded filaments bear to frog-spawn, are 

 now ranked as humble fresh-water forms of a far higher, chiefly 

 marine, group of algae, the Rhodospermece, or red sea-weeds. But 

 they deserve special notice here on account of the simplicity of their 

 structure, and the extreme beauty of the objects they afford to the 

 microscopist (fig. 433). They are chiefly found in water which is 

 pure and gently flowing. * They are so extremely flexible,' says Dr. 

 Hassall, ' that they obey the slightest motion of the fluid which 

 surrounds them ; and nothing can surpass the ease and grace of 

 their movements. When removed from the water they lose all 

 form, and appear like pieces of jelly, without trace of organisation ; 

 on immersion, however, the branches quickly resume their former 

 disposition.' Their colour is for the most part of a brownish green, 

 but sometimes they are of a reddish or bluish purple. The central 

 axis of each plant is at first composed of a single filament of large 

 cylindrical cells laid end to end ; but this is subsequently invested 

 by other cells, in the manner to be presently described. It bears 

 at pretty regular intervals whorls of short radiating branches, each 

 of which is composed of rounded cells, arranged in a bead-like row, 

 and sometimes subdividing again into two, or themselves giving off 

 lateral branches. Each of the primary branches originates in a little 

 protuberance from the primitive cell of the central axis, precisely 

 after the manner of the lateral cells of Cladophora glomerata ; as this 

 protuberance increases in size, its cavity is cut off by a septum, so 

 as to render it an independent cell ; and by the continual repetition 

 of the process of binary subdivision this single cell becomes con- 

 verted into a beaded filament. Certain of these branches, however 

 instead of radiating from the main axis, grow downwards upon it, 

 so as to form a closely fitting investment that seems properly to 

 belong to it. Some of the radiating branches grow out into long- 

 transparent bristles, like those of the Chcetophoracece; and within 

 those are produced antherozoids, which, though not endowed with 

 the power of spontaneous movement, find their way to the oospheres 

 contained in other parts of the filaments ; and by the fertilisation 

 of the contents of these are produced the somewhat complicated 

 fructifications known as cystocarps, placed in the axils of the 

 branches (fig. 433). 



