SIMPLE PLANTS 



207 



velop into young plants. The question as to the chromosome number 

 in the cells of plants formed by artificial fertilization is of very great in- 

 terest, but has not yet been investigated." 



It must be remembered that the egg was already there. Artificial 

 fertilization merely hastened a normal action. This does not throw any 

 light on the origin of life, as is popularly supposed. 



VAUCHERIA 



This is the common "green felt" (Fig. 86), usually found on soil, 

 though it is often found in water. The thread-like filaments are coarser 

 and longer than spirogyra and they also branch. Vaucheria are tube 

 algae. 



There is an interesting difference here from the spirogyra in that 

 there are no transverse cell-walls throughout the entire filament, but 

 there are many nuclei scattered about. Such a form is called a coenocyte 

 ( ) or syncytium (I. E., Fig. 86). 



Fig. 100. Ascomycetes (Sac-like Fungi). 



The figure shows the characteristic group- 

 ing of asci. The layer in which the asci ap- 

 pear is called a hymenium. In these th 

 mycelium has dividing septae and the spores 

 are contained in asci. (After Chamberlain.) 



Fig. 101. Basidiomycetes. 



Typical basidium with sterigmata (distal 

 short stalks), showing spores in different 

 stages of development. (After De Bary.) 



In basidiomycetes the spores develop on 

 little club-shaped hyphae. Smuts, rusts and 

 mushrooms belong in this group. 



Reproduction takes place both sexually and asexually (Fig. 86). In 

 the latter case the old end of the filament dies, setting free the branches 

 which become separate plants, or a cross wall forms in one of the 

 branches. A thickening occurs beyond this cross wall and this thick- 

 ening is known as a zoospore. The zoospore breaks away from the par- 

 ent plant, swimming about for a time and then becomes a new plant. 



