THE WAT IN WHICH NEW PLANTS ARISE 139 



placed on damp soil covered witli a dish in a warm 

 room, they may be seen to germinate. 



192. Reproduction hy 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 hy 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, 



