172 THE OLDER HYBRIDISTS 
found in a considerable number of cases that the off- 
spring resembled one parent only, from which it was 
indeed indistinguishable, whilst no trace of likeness 
to the second parent could be detected in it. In some 
cases the resemblance was to the paternal species 
(pollen-parent), and in others to the maternal species 
(seed-parent). In several instances the hybrid off- 
spring, on being self-fertilized, bred true to the type 
which they already exhibited, so that the second 
generation, like the first, seemed to derive its whole 
constitution from one parent, to the total exclusion 
of the other. 
The precise meaning of this remarkable phenomenon 
is not clearly understood. There is some doubt as to 
whether Millardet’s experiments were really sufficient 
to establish it as a scientific fact. Moreover, Millar- 
det’s observations have never been confirmed by later 
workers. In the absence of directly contradictory 
evidence it seemed necessary to draw attention to the 
facts as they have been described. 
Great numbers of observations upon the character- 
istics and behaviour of hybrid plants and animals have 
been from time to time recorded, and the preceding 
pages contain only a brief selection of such facts as 
are most necessary for a proper understanding of 
modern work in hybridization. Until quite recently 
the laws of transmission of characters in hybrids were 
still completely hidden. The facts were wonderful 
enough, but they showed no signs of falling into an 
orderly arrangement. In the next chapter it will be 
our business to describe the remarkable discovery 
