362 W. B. Scott — Variations and Mutations. 



on the two sides of the month or with regard to the upper and 

 lower jaws, but much more frequently is not so! (3) In many 

 cases of increased number of teeth it appears that two teeth 

 in the variant represent one in the normal and have arisen by 

 the division of a single tooth-germ. (4) Most cases of numer- 

 ical variation of teeth affect those standing at the beginning or 

 ends of series. (5) New teeth arising in particular places 

 have a more or less constant size and the size of such a tooth 

 is often related to that of adjacent teeth and to the general 

 curves of the series. (6) The teeth next to which new ones 

 arise may vary in correlation with them. (7) A few cases 

 6how the members of a series to have been remodelled so that 

 their supposed individuality has been lost. (8) Individuality 

 should not be attributed to members of a series which has 

 normally a definite number of members. 



The results of the examination of varying digits may be 

 summed up as follows : (1) The frequency of digital variation 

 differs greatly in different animals. (2) In particular animals 

 the variation tends to approximate particular types. (3) The 

 variation may affect both sides similarly and simultaneously, 

 though usually differing in degree on the two sides. Similar 

 and simultaneous variations frequently occur in both manus 

 and pes, though rarely identical in the two. (4) When a digit 

 is added, the adjacent one may be modified in accordance with 

 its new place in the series. (5) There is no sharp distinction 

 between the duplicity of a given digit and other modes of 

 addition to the series. (6) Digital variation is often markedly 

 discontinuous. (7) No distinction can well be drawn between 

 those variations which resemble the normal condition of other 

 animals and those which do not. 



" The attribution of strict individuality to each member of 

 a series of repeated parts leads to absurdity and in variation 

 such individuality may be set aside, even in a series of differ- 

 entiated members. It appears that the number of the series 

 may be increased in several ways not absolutely distinct, that a 

 single member of the series may be represented by two mem- 

 bers, that a terminal member may be added to the series, and 

 also that the number of the members may change, no member 

 precisely corresponding in the new total to any one member of 

 the old series ; in short, that with numerical change result- 

 ing from meristic variation [i. e. variation in the number of 

 repeated parts] there may be a redistribution of differentia- 

 tion." (p. 570). 



These are most important and far reaching conclusions, 

 which, if established, will profoundly modify many of the 

 current conceptions of morphology. That they follow fairly 

 from the evidence of variation presented in the body of the 



