Lnheritance of Acquired Characters ae7 
These laws are, Lamarck says, fundamental truths which 
cannot be misunderstood except by those who have never 
observed or followed nature in her operations. He insists 
that it is a mistake to suppose that the parts are responsible 
for the functions, for it is easy to demonstrate that it is the 
needs and uses of the organs that have caused the parts to 
develop. 
If it is supposed, he continues, that these laws are hypo- 
thetical, they may be demonstrated by the following facts: 
The adult baleen whale is without teeth, although in the 
foetus teeth are present, concealed in the jaws. The loss 
of the teeth is the result of the whale swallowing its food 
without first masticating it. The ant-eater is also without 
teeth, and has also the habit of swallowing its food without 
chewing it. The mole has very small eyes, and this is the 
result of its having made very little use of them, since its 
habits are subterranean. Another animal, the aspalax, has 
only the rudiments of eyes, and has almost completely lost 
the power of sight. This animal also lives underground like 
the mole. 
Proteus, an aquatic salamander living in deep caves, has 
only rudimentary eyes. In these latter cases it is the disuse 
of the eye that has led to its degeneration. This is proven, 
Lamarck adds, by the fact that the organs of hearing are 
never in this condition, because sound vibrations penetrate 
everywhere, even into the densest bodies. 
It is a part of the plan of organization of the reptiles that 
they have four legs; but the snakes, although belonging to 
this group, have no legs. This absence of legs is explained 
by their having acquired the habit of gliding over the ground, 
and of concealing themselves in the grass. Owing to their 
repeated effort to elongate themselves, in order to pass 
through narrow spaces, their bodies have become drawn out. 
Under these circumstances legs would be useless, since long 
ones would interfere with their motion, and short ones could 
