240 ELEMENTS OF SCIENCE 



directly from the inorganic world. With the exception 

 of fungi and some parasitic plants (such as the dodder), 

 the whole vegetable world is continually engaged, during 

 the hours of daylight, in tearing from the atmosphere 

 its carbon, and in absorbing moisture in order to build 

 up substances capable of life. 



The repair of injuries and reproduction of lost parts 

 take place in lower animals to a much greater extent 

 than it does in the one selected as our type the cat. 

 The tails of lizards, the limbs of efts, and the legs and 

 claws of lobsters, if broken off, will be reproduced, and 

 some aquatic worms have been cut into as many as 

 twenty-five parts, with the result that each separated 

 part has grown into a whole. Some polyp-animals 

 form buds (like those before spoken of as being pro- 

 duced by tiger lilies), which will often become detached, 

 and then grow up into new individuals, like those plants 

 which will give forth " suckers " and then separate. 

 The common bramble will attach itself to the ground 

 by the end of a "shoot," rootlets coming to take the 

 place of the incipient leaves of its terminal bud, and 

 so a new stem is formed. 



Thus "growth" is " continuous reproduction," and 

 " reproduction " is a form of growth which may be 

 "continuous" or "discontinuous." Continuous repro- 

 duction occurs in animals as well as in plants, and thus 

 it is that many coral animals grow up as arborescent 

 structures, or into large masses leading to the formation 

 of reefs and islands. Discontinuous growth may occur 

 in certain worms, which habitually divide themselves and 

 so multiply, and multitudes of Protozoa, as before said, 

 multiply by spontaneous fission. 



The circuitous course of development of the embryo, 

 before mentioned as taking place in the kitten, is pursued 



