THE WAT IN WHICH NEW PLANTS ARISE 139 



placed on damp soil covered with a dish in a warm 

 room, they may be seen to germinate. 



192. Reproduction by spores. Instead of cut- 

 ting off a member of its body for the purpose of 

 giving rise to new individuals, the plant may develop 

 special masses of reproductive tissue. When these 

 masses reach maturity, they divide into a number 

 of separate cells, each of which is capable of giving 

 rise to a new individual upon germination. The 

 origin of new individuals in this manner is termed 

 asexual reproduction, and the spores in a puff ball, 

 or those on the under side of a fern leaf, exhibit 

 this action. 



193. Reproduction by eggs. In another method 

 of reproduction the plant develops two kinds of 

 reproductive tissue, and when these are mature a 

 cell from each unite to form a fertilized egg, which 

 then is capable of giving rise to a new individual. 

 The two kinds of reproductive elements are termed 

 gametes, and the origin of new plants by this method 

 constitutes sexual reproduction. 



194. Fern spores. Examine the under side of 

 the leaves or fronds of the polypody or any com- 

 mon fern in the autumn. A number of brown spots, 



