PLATE XIX.-STONEWORT (Chara). 



{Development after Pringtheim). 



Chara may be found growing in ponds and streams, varying in height from a few inches to several feet. It is entirely submerged 

 and the stem is often encrusted with calcareous matter derived from the water, which makes it exceedingly brittle. In bog-pools, 

 however, where the water is soft they may be found free from this, and so more useful for purposes of study. 



This plant differs from those hitherto considered in possessing an Axis and Appendages. The Axis grows in the direction of its 

 length and is furnished with an apical cell, by the division of which growth is continued. Certain cells of the stem have also different 

 functions assigned to them. The Lateral Appendages arise from one kind of cell while another kind is much longer and form the main 

 part of the axis. 



Fig. 1. Portion of Chara in Fruit. 



It is composed of a long thread-like stem, giving off at intervals appendages arranged in whorls, and ending in 

 a terminal bud. The place where each whorl of appendages comes off is called a Node, and the space between 

 two nodes is called an Internode. An internode and node with its appendages forms a Segment, and the whole axis 

 is thus a repetition of similar segments. Branches or secondary axes repeating the structure of the primary axis, 

 arise from the angle between the leaves and the stem. 



Fig. 2. Harden specimens in a weak solution of chromic acid, which also dissolves any limy incrustation, then get as small a 

 portion as possible of the terminal bud and press it out, without destroying it, in glycerine. 



The apical cell or growing point is a nucleated hemispherical celL It is hemispherical, for its free rounded 

 surface is not influenced by pressure, while the under surface is flat, being pressed against its neighbour. Below the 

 second cell, which is flat on both surfaces, comes three cells formed from a single cell by vertical divisions. Next 

 is an undivided cell, followed by a divided cell. 



Fig. 3. Fertile leaf detached. 



Antheridia or Male Organs, globular. 

 Carpogonia or Female Organs, more elongated. 



Fig. 4. Portion of same enlarged. 



The Antheridia and Carpogonia arise from a node, and the leaflets or bracteoles protect them. 



Fig. 5. Tease out a ripe Antheridium and examine portions under highest power of microscope. 



The essential parts are the filaments divided into numerous cells, each containing an Antherozoid. 



Pig. 6. The liberated antherozoid is seen to have two long cilia at the tapering end and granular contents at the blunt end. 



Figs. 7, 8, and 9. The spores on germination gives rise to a Primary Rootlet and a Pro-embryo, one of the cells of which 

 buds forth and produces a Chara. 



Life History of Chara. — Chara produces Antheridia with Antherozoids and Carpogonia with their central cells. The antherozoids 

 fertilise the central cell of the Carpogonium thus converting it into an Oospore. This germinates and produces a Pro- 

 embryo, from a bud of which Chara is developed. 



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