ON HYBEID] ZATION AMONG PLANTS. 
311 
These unstable forms want the true character of species from 
the very fact that they cannot with any certainty reproduce 
themselves by seed. Those species which have a tendency to 
vary, do so in a very different manner to hybrids, for the 
variety has a tendency to perpetuate itself and increase, and 
not to be unstable, as in hybrids. Hence can arise garden 
“ races,” an inapplicable term to the unstable “ forms '' of 
hybrid descendants. “ Races bring species which are adapting 
themselves to new media and new finalities.” 
We may here insert two reasons for the want of permanency 
in hybrids. One, as Wichura has shown in the case of willows, 
is the constantly increasing sterility in the pollen ; and secondly, 
the constitution of the hybrid being often intermediate between 
those of the two parents, it cannot adapt itself to localities 
suited to either. 
5. Reversion to the parent forms. — This subject, to which 
brief allusion has just been made, was that to which M. 
Haudin paid particular attention, viz., to ascertain whether 
reversion was a universal rule or only partially applicable, or 
not at all. 
Our author's account of certain experiments conducted at 
the Museum with a view to ascertaining the truth of the above 
statement will be found in the Ann. des Sc. Nat., 4th series, 
Ho. IX., p. 257 (1858), where he commences by observing 
that M. Godron has come to an opposite conclusion, for he says 
that “ fertile hybrids do not ordinarily revert, unless fecundated 
afresh by one or other of the parent forms, and as a conse- 
quence it appears to him (M. Godron) very doubtful whether 
the law above assumed is really established.” 
M. Haudin makes his statement in the following words : — 
Hybrids, self-fertile or otherwise, return sooner or later to the specific 
types from which they were derived ; and this return is effected either by the 
separation of the two mixed essences or by the gradual extinction of one of 
the two. In the latter case the hybrid posterity returns entirely and exclu- 
sively to one only of the two producing species. 
The examples which he takes as instances of reversion are 
Primula officinali-grandiflora, hybrids of Datura Stramonium , 
reciprocal hybrids of Nicotiana angustifolia, macrophylla, 
Petunia violacea and nyctagini flora, Luffa acutangulo - 
cylindrica, and Linaria purpurea-vulgar is. 
We will now turn to our author's experiments and adjoin a 
few remarks. 
First, with regard to the hybrid primula. Of the second 
generation, raised in 1855, there were seven plants ; one alone 
resembled the hybrid, and was . sterile ; three took the 
characters of P. officinalis; three, those of P. grandiflora (var. 
