560 THE AMERICAN NATURALIST. 
ings. What we actually know without contradiction is that like 
never begets absolute likeness, nor yet absolute unlikeness. It is, 
then, doing a violence to all our observation of nature to make the 
law “like begets like” mean absolute duplication of parent in off- 
spring. It is not good English to make likeness mean identity, unless 
it be by special definition. Things are like which are similar. And 
if the old statement that “like begets like ” is read to mean “similar 
begets similar,” we have a statement of the obvious truth. And, 
moreover, there is no reason to suppose that the course of reproduc- 
tion was ever different. 
In this view of the case heredity and variability belong in the same 
scale. I have been in the habit of illustrating this relation by refer- 
ence to heat and cold in the thermal scale. More cold means simply 
less heat. More variability means simply less rigid heredity. As 
the power of heredity wanes, variability waxes. And so, just as the 
physicist, for the sake. of an accurate terminology, speaks only of 
heat, the biologist ought to have one general name for the one great 
law of reproduction. The term “ heredity ” would answer all purposes, 
had its proper meaning not already been clouded by the attachment 
of unwarranted definitions to it, and were its etymology not also a 
trifle awkward for the uses required. In fact we all speak of varia- 
bility hundreds. of times when we would speak of heredity, were it 
not for the convenient adjective “ variable ” with its easy compari- 
sons. Partly to get away from false ideas of heredity, and partly 
to keep clear the unity of the reproductive law, I have adopted an- 
other word for use in my classes, and now speak of “ the allophysical 
law.” If the allophysical law were to be stated, it would be in the 
words “ similar begets similar ” (‘ like begets similar ” would be more 
logical, no doubt ; but it is easier to stick to the old order), or in the 
words “ like begets like,” properly explained. 
If some one will give us a simple word to take the place of heredity 
and variability in their combined meaning, and one which shall be 
accompanied by some manageable and easily compared ses spurt it 
will be a great conyenience to future discussion. 
FRANK A. WAUGH. 
UNIVERSITY OF VERMONT. 
