THE STRUCTURE OF PROTOPLASM 
Data from Cytology 
In considering the modern cytological viewpoint as to the structure of 
the cell, I may first indicate the general sense in which I shall use the terms 
relating to the cell and its parts. And I must state at once that nothing is 
further from my intention than to attempt to provide a series of hard and 
fast definitions of structures as fluctuating and plastic as are the cell and 
the materials of which it is composed. A word is perhaps necessary here 
as to the place of definitions in modern science. It is frequently stated that 
science progresses with the increasing clearness of our definitions, and that 
much useless controversy would be avoided if contestants were compelled 
to define their terms. It seems to me that in these statements modern 
science is accepting and perpetuating a mediaeval dogma which since Dar- 
win has practically lost its significance. In the days of metaphysics and 
the use of the deductive method in logic, it was of vast importance to know 
just how much was implied in any term used in a major premise, for on that 
and that alone depended how much could be gotten out of it in conclusions. 
Especially when certain conceptions or ideas were assumed to be self- 
evident or axiomatic, it was vital to know just how much was implied in a 
given term as self-evident. With modern science, so-called axioms as 
relating to any matters of scientific importance have largely gone the way 
of all the earth. With a realization of the supremacy of the inductive 
method we become less restrictive in our use of terms in our larger interest 
as to what is really true of the subjects to which they relate. Relatively 
few modern controversies are due to misunderstanding of each other by 
the principals. In the dispute between Weismann and Spencer over the 
inheritance of acquired characters it was no mere matter of terms, and in 
the flare-up over the meaning of the word genotype which followed the 
visit of Johannsen to this country the obscurity was all in the facts about 
the constitution of the germ plasm rather than in the various definitions 
and usages proposed for the term. There is a positive danger in the use of 
definitions which is obvious in the discussion of the factorial hypothesis 
raging just now. There is a group of geneticists- who would frame a defi- 
nition of the term unit factor so very broad and so empty of all concrete 
and specific implications that it would become an abstraction like many of 
the conceptions of mathematics. This is the aim of those who would make 
Mendelism a system of notation. A mere one factor conjugated with one 
factor makes two factors, and one factor separated from the other factor 
gives two independent factors. Representatives of these tendencies 
sometimes try to win support by accusing their opponents of ignorance 
that one and one make two and one from two leaves one. No one disputes 
such mathematical obviousness, but it is the death of science when concrete 
realities are attenuated to fit such empty generalizations. It is of the very 
essence of modern scientific method and spirit that it has broken away from 
such formalism and resists the temptation of the human mind to accept 
