284 LAMARCK, HIS LIFE AND WORK 
which circumstances have forced to change in climate, 
mode of life, and habits; but in their case the in- 
fluences of the causes which I have just cited need 
still more time than the plants to bring about notable 
changes in the individuals. 
“The idea of embracing, under the name of speczes, 
a collection of like individuals which are perpetuated 
by generation, and which have remained the same as 
long as nature has endured, implies the necessity 
that the individuals of one and the same species 
should not cross with individuals of a different species. 
“Unfortunately observation has proved, and still 
proves every day, that this consideration is un- 
founded; for hybrids, very common among plants, 
and the pairings which we often observe between the 
individuals of very different sfeczes of animals, have 
led us to see that the limits between these supposed 
constant species are not so fixed as has been imagined. 
“Tn truth, nothing often results from these singu- 
lar unions, especially if they are very ill-assorted, and 
then the individuals which do result from them are 
usually infertile; but also, when the disparities are 
less great, we know that the default in question does 
not occur. 
“But this cause only suffices to create, step by 
step, varieties which finally become races, and which, 
with time, constitute what we call speczes. 
“To decide whether the idea which is formed of 
the species has any real foundation, let us return to 
the considerations which I have already explained ; 
they lead us to see: 
“1, That all the organized bodies of our globe are 
true productions of Nature, which she has succes- 
sively formed after the lapse of much time ; 
“2, That, in her course, Nature has begun, and 
begins over again every day, to form the simplest or- 
ganisms, and that she directly creates only those, 
namely, which are the first germs (¢bauches) of organ- 
