224 



THALLOPHYTA. 



[CH. 



leaf-node. The tips of the investing cells project at the apex 

 in the form of a terminal crown or corona (fig. 45, E, c). The 

 antheridia have a complex structure, and produce a very large 

 number of motile antherozoids. 



Fm. 45. A and B. Chara Knowltoni Sew. From a section in the British 

 Museum. C. Stem of Chara foetida A. Br. in transverse section (after 

 Migula. X 18). D. Interior of oogonium of G. foetida. E. Oogonium 

 of C. foetida (D and E after Migula. x 50). 



After fertilisation, the egg-cell becomes surrounded by a 

 membrane, at first colourless, but afterwards yellow or brown. 

 The inner cell-walls of the cells surrounding the oospore become 

 thicker and darker in colour ; the outer walls remain thin and 

 eventually fall away. The lateral walls may or may not 

 become thickened. In most of the Chareae a calcareous deposit 

 is formed between the hard shell and the outer walls of the 

 cells enveloping the oospore. This calcareous shell is developed 

 subsequently to the thickening and hardening of the inner 



