40 BOTANY, 



walls passing through the centre. In each of these eight cells two walls are 

 next formed parallel to the outer surface, so that the antheridium (apart 

 from the basal cell) contains twenty- four cells arranged in three concentric 

 series (G, an.). These cells, especially the outer ones, develop a great 

 amount of a red pigment, giving the antheridium its characteristic color. 



The diameter of the antheridium now increases rapidly, and the central 

 cells separate, leaving a large space within. Of the inner cells, the second 

 series, while not increasing in diameter, elongate, assuming an oblong 

 form, and from the innermost are developed long filaments (7, J) com- 

 posed of a single row of cells, in each of which is formed a spermatozoid. 



The eight outer cells are nearly triangular in outline, fitting together by 

 deeply indented margins, and having the oblong cells with the attached 

 filaments upon their inner faces. 



If a ripe antheridium is crushed in a drop of water, after lying a few 

 minutes the spermatozoids will escape through small openings in the side 

 of the cells. They are much larger than any we have met with. Each 

 is a colorless, spiral thread with about three coils, one end being some- 

 what dilated with a few granules ; the other more pointed, and bearing 

 two extremely long and delicate cilia (K). To see the cilia it is necessary 

 to kill the spermatozoids with iodine or some other reagent. 



After fertilization the outer cells of the oogonium become very hard, and 

 the whole falls off, germinating after a sufficient period of rest. 



According to the accounts of Pringsheim and others, the 

 young plant consists at first of a row of elongated cells, upon 

 which a bud is formed that develops into the perfect plant. 



There are two families of the Characece, the Charece, of 

 which Chara is the type, and the Nitellece, represented by 

 various species of Nitella and Tolypella. The second family 

 have the internodes without any cortex that is, consisting 

 of a single long cell ; and the crown at the top of the oogo- 

 nium is composed of ten cells instead of five. They are also 

 destitute of the limy coating of the Charece. 



Both as regards the structure of the plant itself, as well as 

 the reproductive organs, especially the very complex antheri- 

 dium, the Characece, are very widely separated from any other 

 group of plants, either above or below them. 



