436 KINSHIP AND ADAPTATION 
tracing of kinship that it is often obscured by the workings of other 
laws. Recapitulation is understood to be a consequence of the 
general rule that organisms inherit as far as possible all the pecul- 
jarities of their ancestors, and so have similar young stages; but 
new features may appear even in the young which can be inherited 
only by obscuring or obliterating the old. 
Sometimes bluebell flowers are found having distinct petals, 
and so resembling what evolutionists suppose to have been the 
remote ancestral form. Such exceptional adult forms resembling 
younger stages or presenting features which on other evidence may 
be regarded as ancestral, are classed as reversions. It is a common 
experience of breeders to observe some striking peculiarity of an 
animal or plant disappear in the first generation of offspring and 
then reappear in those of the second or some subsequent generation. 
This reappearance is called atavism ' and seems to differ from re- — 
version only in the remoteness of the ancestor to which the descend- 
ant reverts. Reversions are of interest to the evolutionist as often 
affording confirmation of views of kinship otherwise made probable. 
It should be borne in mind, however, that many abnormalities have 
no claim to be called reversions. 
Another clue to kinship is found in rudimentary organs, 
such for example as the imperfectly developed ovules of 
anemonies. The presence of these presumably useless organs 
may be explained by supposing them to be vestiges inherited 
from an ancestor which had in each ovary several perfect 
ovules; and when we find such a plant as the marsh-marigold, 
very like an anemony except for having perfect ovules in 
place of the rudimentary ones, our conviction that these 
plants are closely akin is much strengthened. Furthermore, 
these rudimentary ovules in anemonies serve to bridge the 
gulf which separates those members of the crowfoot family 
which have several ovules from those which have only a 
single one in each ovary, for they seem to preserve a stage 
in the process by which several ovules were crowded out. 
In the light of what we have learned of the general principles of 
evolution let us now re-examine the members of the Ranunculaceze 
represented in the family chain on page 353, and see to what more 
definite conceptions they may lead us. The family chain diagram 
may be taken to represent a top view of the branches of a family 
tree, the rectangles standing for living genera, and the links connect- 
ing them for the forks of extinct or buried branches. This same 
family tree viewed from the side, the branches being swung round 
1 At/a-vism < L. atavus, a great-grandfather’s grandfather. 
