244 BIOLOGY 



plant, for example, sends out branches which grow for some 

 distance, and then their tips strike root into the ground and 

 a new plant springs up, united with the old one at first by a 

 connecting branch; Fig. 113. 



Among animals this method of reproduction is not so common 

 as in plants and is confined to the lower species. One example 

 has been already described in Hydra; see page 146. 



Reproduction by division is evidently closely related to the 

 power of replacing lost parts. Hydra may be divided into many 



FIG. 113. REPRODUCTION IN A STRAWBERRY PLANT BY DIVISION 



pieces, each capable of producing all of its lacking parts; but 

 this power is retained in diminishing degree as we go from 

 lower to higher animals. The earthworm does not ordinarily 

 multiply by simple division, but if it is cut into two pieces by 

 accident, each will develop the lost parts and two animals 

 will result. In some worms, related to the earthworm, this 

 method of multiplication by division, each piece developing all 

 of the lost parts, is a normal method of reproduction; Fig. 114. 

 Reproduction by Spores. Reproduction by means of spores 

 is also found among the multicellular organisms, especially 

 among the multicellular plants. A few illustrations of it are 

 the following: 



