256 



VEGETATIVE PROPAGATION 



A piece of stem cut from certain plants and placed 

 in water or moist sand will grow roots. 



plant. Geraniums and other house plants are usually propagated 

 in this way since they may be produced much more quickly from 



cuttings or slips than from 

 the germination of seeds. 

 Another advantage of slip- 

 planting is that one is usu- 

 all}' sure to grow a plant true 

 to the type from which the 

 slip was taken. The seeds 

 of plants do not always 

 develop into plants exactly 

 like the organisms from 

 which they were gathered. 



Regeneration. There is a 

 type of propagation found 

 among certain animals that 

 is somewhat similar to cuttings of plants. It is possible for many 

 organisms to reproduce lost parts and grow into complete individ- 

 uals. The common earthworm is a good example. If a worm 

 is cut through the middle, each half may develop the missing parts 

 and each part may become a complete worm. Certain flat worms 

 may be divided into several parts and each part will become a 

 complete individual. Sponges are propagated by cutting a sponge 

 into many sections and sowing the ocean floor with them. Each 

 section will develop into a complete organism. The regrowth or 

 reproduction of the parts of an organism which have been lost or 

 destroyed is called regeneration. If some animals such as crusta- 

 ceans (lobsters, crabs, shrimps) and echinoderms (starfishes, sea 

 urchins, sea cucumbers) lose one of their appendages or rays, they 

 are able to regenerate these parts. Sometimes a lobster is seen 

 with one claw much larger than the other. This probably indi- 

 cates that the smaller is a second growth, the first having been 

 lost in a fight or through an accident. 



