INTRODUCTION. 3 



till in man, whose complex organization is wielded by an un- 

 dying intelligence, we have a being in whose hands the dead 

 matter of the universe is obedient as plastic wax. f. If our 

 observation be continued for a sufficient length of time, we 

 always discover that every living body has the power, by more 

 or less complex process, of reproducing its like. That is to 

 say, it has the power, directly or indirectly, of giving origin 

 to minute germs, which can be developed under proper con- 

 ditions into the likeness of the parent, g. Lastly, all living 

 beings alike appear to be primitively composed of a substance 

 which is more or less closely allied to albumen or white-of-egg, 

 and which has been termed "protoplasm." Vital phenomena 

 can apparently be manifested by no other form of matter, and 

 protoplasm bears to life the same relation that a conductor 

 does to the electric current. It is the necessary vehicle and 

 medium through which life is brought into relation with the 

 outer world. It does not, however, follow from this, as has 

 been assumed, that protoplasmic matter holds any other or 

 higher relation to life, or that vital phenomena are in any 

 way an inherent property of the matter by which they are 

 manifested. 



All the objects, then, which fulfil these conditions, are said 

 to be alive ; and they all belong either to the animal or to the 

 vegetable kingdom.* The study of living objects of all kinds, 

 irrespective of which kingdom they belong to, is conveniently 

 called by the general name of Biology (Gr. Mos, life; and 

 logos, discourse). As all living objects, however, may be re- 

 ferred to one or other of these two kingdoms, so Biology may 

 be divided into the two sciences of Botany, which treats of 

 plants, and Zoology (Gr. zoon, animal ; logos, discourse), which 

 treats of animals. The term Natural History, again, is gen- 

 erally understood nowadays as being equivalent to Zoology 

 alone, though originally it was applied to the study of all 

 natural objects indiscriminately. 



2. DIFFERENCES BETWEEN ANIMALS AND PLANTS. 



It now becomes necessary to inquire into the differences 

 which subsist between animals and plants, and which enable 

 us to separate the kindred sciences of Zoology and Botany. It 

 might have been thought that nothing could be easier than to 



4 * As will be mentioned immediately, it has been proposed to form an intermediate king- 

 dom between the animal and vegetable kingdoms for the reception of organisms which 

 cannot certainly be stated to be either plants or animals. There does not appear, however, 

 to be any necessity for this in the mean while. 



