ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 101 



The movements of the zoospores in water are greatly influenced 

 by light, collecting towards the source of light beneath the cover-glass, 

 and even moving towards it with great rapidity. If the cover-glass is 

 removed they swim upon the surface of the water in a very peculiar 

 way. The zoospore dips beneath the surface of the water, comes to 

 rest, rounds itself off, and then bores through the surface as if it were 

 a solid membrane, by means of a protuberance which thus elevates 

 itself in the air, and gradually increases in size as the part below the 

 surface diminishes, and finally disappears, so that the zoospore is now 

 entirely exposed. This process recalls the mode in which the zoo- 

 spores of the ChytridiaccEe penetrate the tissue of their host. A close 

 examination shows that during this process the zoospore has enveloped 

 itself with a delicate colourless envelope of gelatine, which has a 

 tubular opening below through which the zoospore absorbs water. 



If left for a time undistui'bed on the surface of the water, the 

 encysted zoospore begins to multiply by bipartition, 2, 4, or 8 cells 

 being formed within the common envelope, the entire organism varying 

 in size according to the number of enclosed cells. These constitute 

 the yellow dust with which the observation started ; the larger 

 particles being formed by the coalescence of a number of the gelatinous 

 envelopes of smaller particles, as can be readily followed step by step 

 under the Microscope. Not the least trace of a union or conjugation 

 of the individual zoospores within the envelope can be made out. Each 

 individual, moreover, retains its tubular projection beneath the surface 

 of the water ; the number of these being therefore large in the larger 

 particles. These tubes are, however, only clearly seen when the 

 particle is immersed in water, being of a firmer consistency and not 

 swelling up like the rest of the envelope. As soon as the swelling has 

 taken place, the zoospores escape into the surrounding water, and 

 begin to move about actively. They soon move towards the light, and 

 reaching the surface of the water, go through the same process again. 



On some of the pools was found also a coating of a much finer dust, 

 a microscopical examination of which showed it to be of precisely the 

 same composition as the coarser. The swarm-cells are extremely 

 minute, always spherical, uniciliated, and provided with one or two 

 pigment-spots of a pale brown or greenish-yellow colour. The author 

 was unable to determine with certainty whether these are an inde- 

 pendent organism, but inclines to the view that they belong to the 

 same cycle of development as Chromophyton Bosanoffii. 



Great interest attaches to the wintering of this organism, which 

 takes place within the leaves and stem of Sphagnum. It is well known 

 that various lowly organized Algte, such asNostoc, Anabcena, Oscillaria, 

 Chlorococcum, &c,, are found within the large empty cells of Sphagnum ; 

 the peculiarity of the Chromophyton is that it enters not only these, 

 but also the small cells between them, through the cell-wall of which 

 they must bore their way, but apparently only in those which no longer 

 contain chlorophyll. It chooses also other aquatic mosses, as an 

 undetermined species of Hypnum, for its winter quarters, but here again 

 only the cells destitute of chlorophyll. 



Within the host, although no cilia are yet to be seen, the Chromo- 



