292 



ELEMENTARY BIOLOGY 



339. Budding cells. In some organisms new cells are pro- 

 duced in a different way. The yeast plant, for example, which 

 absorbs its food from the surrounding liquid, continues to 

 grow indefinitely without undergoing cell division. When a 

 cell has reached a certain size, it puts forth one or several 



B 



Fig. 125. Spores in fungi 



A . In the black molds, reproductive cells (spores) are formed by the repeated division of 

 the protoplasm in an enlarging cell at the end of a thread. When mature, the inclosing 

 wall breaks and the spores are scattered. B : In the blue molds, spores are formed by 

 the successive separation of terminal portions of the branched threads. This is a type 

 of fungus used in ripening Camembert cheese 



swellings. As all of the exposed surface of the original cell and 

 of the buds absorbs food and water, the protoplasm grows, and 

 the buds may put forth buds in turn (see Fig. 5,5, and Fig. 124). 

 A bud sometimes drops down ; it then continues its growth 

 and its budding, like a new cell. In an organism of this kind 

 the buds are to be considered as new cells or as parts of the 

 parent cell. It is a matter of chance when the bud drops off 

 and begins to live independently. This is another case of what 

 is called discoiitiniwus grozvth (see p. 269), 



