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is, in response to the need or desire of the animal — the ear, through 

 heredity, would gradually revert to that of the wild boar. And in a 

 similar way the tame pig would gradually lose all its character due to 

 domesticity, and assume those compatible with a wild life. And we see 

 the same gradual modification of ear in dogs that hunt by scent (e.g. the 

 blood-hound), the ears, relatively little used, gradually enlarge, and 

 become more and more pendent. 



It may be thought that the foregoing has reference only to " use 

 and disuse," and the modification of characters induced thereby ; but to 

 take such a limited view of the changes brought about, in accordance 

 with Lamarck's laws, would be wrong. The laws of Lamarck have 

 reference to changes of a far wider and deeper nature than is understood 

 by the use of the phrase "use and disuse." The modifications of characters 

 produced by changes in the circumstances of animals bear, not only on 

 the use and disuse of special parts, but also on all other auxiliary organs 

 which co-operate in satisfying the wants or needs of animals, which 

 changes in their circumstances have affected. When we consider the 

 many different parts or characters which are brought into co-operative 

 action when an animal, through a change of circumstances, is forced, 

 through its desire for food, to adopt a new method of feeding — when 

 we consider, also, the changes in the nutritive organs, which a radical 

 change in the nature of the food may entail — we begin to realise the 

 many changes, external and internal, which changes in the circumstances 

 of animals may bring about. 



Lamarck's theory, as here developed, explains how, granted that a 

 change of habits in any species may produce changes in special as well 

 as correlated organs, and may affect, not individuals only, but a species 

 as a whole, new species appear in a comparatively short time, owing to 

 the fact that all such modifications of characters are fixed through 

 heredity, thus accounting for the absence of transition forms in many 

 instances — a fact which research proves. 



It may be well to state how, by the Lamarckian theory, the two 

 kinds of characters, innate and acquired, are explained. Innate char- 

 acters, on this theory, are those derived through the wants or needs of 

 the animal, i.e. through the central nervous system. As they are brought 

 about en masse they affect both sexes alike ; hence, through heredity, 

 they become fixed, and the species is modified thereby. Acquired 

 characters, on the other hand, are derived through the surrounding con- 

 ditions, such as climate, etc. Their relation with the nervous system 

 is only through reflex nerves. When the whole of the reflex nerves are 

 affected, as in the case of a tropical sun on the skin, in process of time 

 the central nervous system becomes modified, and the acquired character 

 becomes fixed or innate. On the contrary, characters such as mutila- 

 tions and scars, which only affect a few of the reflex nerves, do not 

 become innate, or capable of being transmitted, because the unaffected 

 reflex nerves, being in the vast majority, maintain the integrity of the 



