208 



General Biology 



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 it is popularly supposed to do. 



VAUCHERIA 



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

 although it is often also 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 

 many nuclei are 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 the 

 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 Barry.) 



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 

 parent plant, swimming about for a time, and then becomes a new 

 plant. 



It is made up of many cells but forms only one plant. 



