61 
[Hyatt. 
ology." This term is open to the objection tliat it is derived from 
av|ti meaning simply progressive growtli up to and inchiding tlie 
adult stage, and although in common with otliers I have felt that 
it has claims to be retained, there are good reasons why it should 
be moi-e restricted in application. 
I have placed two terms at the head of this chapter ]iartl_y 
because I have not had time to consult the proper judges, physi- 
ologists, and obtain their decision, and partly because I am unde- 
cided in my own opinion. Cope in his "Method of creation of 
organic forms''^ used the term bathmism from Pa0(xds, meaning a 
step or threshold, to designate growth force, and it is therefore 
questionable whether the term bathmology should not be sub- 
stituted for auxology in order to give uniformity to the nomen- 
clature. 
It is not necessary to discuss this here, and the facts are merely 
mentioned to call attention to this question and bring out ex- 
pressions of opinion. Physiologists and naturalists universally 
recognize that essential distinctions exist between growth and 
develo])ment of organisms."^ Plerbert Spencer in his ' 'Principles of 
biology" gave these differences with great clearness. He pointed 
out that, as a general conception, the definition of growth, 
increase in mass, is applicable in different ways to all the bodies 
that have arisen through evolution. Physiologists understand the 
science of growth to be an inquiry into the laws that govern the 
increase or reduction of the body and its organs in bulk. Devel- 
opment, on the other hand, is defined by Spencer as follows: ''By 
development, as here to be dealt with apart from growth, is 
meant increase of structure as distinguished from increase of 
mass."^ 
Cope has given a more thorough analysis of the same processes 
in his ''Origin of the fittest" (Preface, p. viii), as follows: — 
1. The law of repetitive addition, in which the structures of 
1 Proc. Amer. phil. soc, v. 12, p. 229-203, Dec. 1871 ; also Origin of the fittest, p. viii. 
2 The word development is often loosely used for increase of bulk bj' growtli, thus 
"the development of an origan" is often spoken of when its growth is meant as well as 
its increase in characteristics. By development is here meant the results of growth 
and heredity as distinguishable in the increase of characteristics and differentiation 
or the decrease of characteristics and retrogression. 
■* The principles of biology, v. 2, p 410, Amer. ed. 1872. 
