VII.] TRANSMISSION OF ACQUIRED CHARACTERS. 425 



mitted. It is true that such characters are sometimes called 

 ' acquired ' in pathological works, but His has rightly insisted 

 that such an obviously inaccurate use of the term ought to be 

 avoided, in order to prevent misunderstanding. If every new 

 character is said to be 'acquired' the term at once loses its 

 scientific value, which lies in the restricted use. If generally'' 

 used, it would mean no more than the word 'new' ; but new 

 characters may arise in various ways, — by artificial or natural 

 selection, by the spontaneous variations of the germ, or by the 

 direct effect of external influences upon the body, including the 

 use and disuse of parts. If we assume that these latter cha- 

 racters are transmitted, the further 'assumption of complicated 

 relations between the organs and the essential substance of 

 the germ becomes necessary' (His), while the transmission 

 of the other kinds of characters do not involve any theoretical 

 difficulties. There is therefore obviously a wide difference 

 between these two groups of characters as far as heredity is 

 concerned, quite apart from the question as to whether acquired 

 characters are really transmitted. It is at all events necessary 

 to have distinct terms which cannot be misunderstood. His ^ 

 has proposed to call those characters which are due to selection 

 'changes produced by breeding' (' erziichtete Abanderungen '), 

 those which appear spontaneously — 'spontaneous changes' 

 (' eingesprengte Abanderungen'), and these two groups of 

 characters would then be opposed to those which he calls 

 ' acquired changes ' (' erworbene Abanderungen '), of course 

 using the term in the restricted sense. Science has always 

 claimed the right of taking certain expressions and applying 

 them in a special sense, and I see no reason why it should not 

 exercise this right in the case of the term ' acquired.' It appears 

 moreover that this w^ord has not always been used in this vague 

 sense by pathological anatomists, sucb as Virchow and Orth ; 

 for Weigert and Ernst Ziegler have employed it in precisely 

 the same sense as that in which it has been used by Darwin, 

 du Bois-Re3'mond, Pfliiger, His and many others, including 

 myself. 



It is certainly necessary to have two terms which distinguish 

 sharply between the two chief groups of characters — the 

 primary characters which first appear in the body itself, and 



* His, ' Unsere KOrperform,' Leipzig, 1874, p. 58. 



