fruin the Cell-contents of the Characeae. 5 



certain circum stances, which appear to be the approaching dis- 

 sokition or death of the cell-wall, a similar process takes place 

 in the cells of the Characese, and following this from the begin- 

 ning, we find, that it first commences with a cessation of the cii'- 

 culation, after which the lines of green disks forming the green 

 layer become displaced, and, as if obeying a still continued but 

 inappreciable movement of the mucus-layer, they roll themselves 

 up into lines which assume a more or less irregular arrange- 

 ment across the internode, or into groups of different sizes, more 

 or less connected by narrow lines of mucus and single disks, so 

 as to present an areolar structure in contact with the inner sur- 

 face of the cell-v;all. The next stage is the separation of the 

 disks into still more distinct groups, which, having become more 

 circumscribed and circular, leave the cell-wall and evince a cer- 

 tain amount of polymorphism and locomotion. The cavity of 

 the iuternode, hitherto rendered turbid by the breaking up of 

 the green layer, now clears off and becomes ti'ansparent, save 

 where the circular masses, which have changed from their ori- 

 ginal green into a brownish-green yellow colour, intercept the 

 light. After a day or two, — but the time seems to vary, — the 

 green disks become entirely brown, and the group, assuming a 

 more circumscribed and circular form, shows that it is sur- 

 rounded by a transparent globular cell ; this we shall henceforth 

 call the gonidial cell. A new substance, consisting of a bluish 

 semitransparent mucus, more or less charged with minute gra- 

 nules (from which its colour appears to be derived), and refrac- 

 tive globules of a faint yellowish-green and sapphire-blue colour, 

 makes its appearance in different parts of the brown mass, or to 

 one side of it, and afterwards, becoming botryoidal or mulberry- 

 shaped, separates into gonidia. The brown chlorophyll with the 

 other eflfete contents then shrinks \\\) into a structureless, homo- 

 geneous, more or less defined, circular nucleus, of a dark brown 

 colour, and the cell, frequently projecting on one side in a 

 conical form, bursts at the apex and gives exit to the gonidia. 



The gonidia are globular, ovate or spindle-shaped, and of a 

 light blue colour. They average 1— 1300th of an inch in dia- 

 meter, and contain, together with the blue substance mentioned, 

 more or less also of the refractive globules, and a transparent 

 vesicle. Each gonidium is provided with one or two cilia accord- 

 ing to its form, that is to say, the globular oncs present one and 

 the spindle-shaped two, which may be perceived while they are 

 yet grouped or separate in the transparent gonidial cell, where 

 they already exhibit a certain amount of polymorphism. Shortly 

 after they have become free in the internodc, the wall of the 

 latter gives way and they pass into the water, where, for a cer- 

 tain time, they remain so active, that it is almost impossible to 



