MONSTROSITIES. 229 
cause of these individual differences, though in detail usually 
utterly unknown to us, depends partly or entirely on certain 
influences which the organs of propagation in the parental 
organism have undergone. 
A second law of indirect adaptation, which we shall 
call the law of monstrous or sudden adaptation, is of less 
importance and less general than the law of individual 
adaptation. ere the divergences of the child-organism 
from the parental form are so striking that, as a rule, we 
may designate them as monstrosities. In many cases they 
are produced, as has been proved by experiments, by the 
parental organism having been subject to-a certain treat- 
ment, and placed under peculiar conditions of nutrition ; for 
example, when air and light are withdrawn from it, or when 
other influences powerfully acting upon its nutrition are 
changed in a certain way. The new condition of existence 
causes a strong and striking modification of form, not 
directly of the organism itself, but only of that of its de- 
scendants. The mode of this influence in detail we cannot 
discover, and we can only in a very general way detect a 
causal connection between the abnormal formation of the 
child and a certain change in the conditions of existence 
of its parents exerting a special influence upon the organs 
of propagation in the latter. The previously mentioned 
phenomenon of albinism probably belongs to this group of 
abnormal or sudden variations, also the individual cases 
of human beings with six fingers and toes, the case of 
the hornless cattle, as well as those of sheep and goats 
with four or six horns. The abnormal deviation in all 
these cases probably owes its origin to a cause which 
at first only affected the reproductive system of the 
