Aug., 1891 . 
ANIMAL PEDIGREES. 
173 
In a sense, all tlie higher animals are degenerate ; that is, 
they can be shown to possess certain organs in a less highly 
developed condition than their ancestors, or even in a rudi¬ 
mentary state. 
Thus a crab as compared with a lobster is degenerate in 
the matter of its tail, a horse as compared with Hipparion in 
regard to its outer toes ; but it is neither customary nor 
advisable to speak of a crab as a degenerate animal compared 
to a lobster ; to do so would be misleading. An animal should 
only be spoken of as degenerate when the retrograde develop¬ 
ment is well marked, and has affected not one or two organs 
only, but the totality of its organisation. 
It is impossible to draw a sharp line in such cases, and to 
limit precisely the use of the term degeneration, It must be 
borne in mind that no animal is at the top of the tree in all 
respects. Man himself is primitive as regards the number of 
his toes, and degenerate in respect to Ins ear muscles ; and 
between two animals even of the same group it may be 
impossible to decide which of the two is to be called the 
higher and which the lower form. 
Thus, to compare an oyster with a mussel. The oyster is 
more primitive than the mussel as regards the position of the 
ventricle of the heart and its relations to the alimentary 
canal; but is more modified in having but a single adductor 
muscle ; and almost certainly degenerate in being devoid of a 
foot. 
Care must also be taken to avoid speaking of an animal 
as degenerate in regard to a particular organ merely because 
that organ is less fully developed than in allied animals. An 
organ is not degenerate unless its present possessor has it in 
a less perfect condition than its ancestors had. 
A man is not degenerate in the matter of the length of 
his neck as compared with a giraffe, nor as compared with an 
elephant in respect of the size of his front teeth, for neither 
elephant nor giraffe enters into the pedigree of man. A man 
is, however, degenerate, whoever his ancestors may have 
been, in regard to his ear muscles ; for he possesses these in 
a rudimentary and functionless condition, which can only be 
explained by descent from some better equipped progenitor. 
We have now considered some of the more important of 
the influences which are recognised as affecting developmental 
history in such a way as to render the recapitulation of 
ancestral stages less complete than it might otherwise be; 
which tend to prevent ontogeny from correctly repeating 
the phylogenetic history. It may at this point reasonably 
be asked whether there is any test by which we can 
determine whether a given larval character is or is not 
ancestral. 
