436 W. E. RITTER AND M. E. JOHNSON 
one comes to think about the matter. For example, reflect on 
the extent to which theories of development and heredity have 
made use of the notion of equation and reduction nuclear divi- 
sions of the germ cells; yet who has determined in any rigid quan- 
titative way the elements that enter into the hypothetical equali- 
ties and inequalities? How familiar is the textbook statement 
that the chromatin of the male fertilization nucleus is ‘exactly 
equal’ to that of the female nucleus with which it fuses! But on 
what sort of determinations does this assertion rest? On scarcely 
another thread of evidence than that they ‘look equal!’ And here 
we come upon the almost incredible naiveté with which biologists 
in most things eminently sound, have gone down before this fal- 
lacy! Only a short time ago while discussing this point with a 
number of biologists, one of them, a man of excellent standing and 
great carefulness in nearly all scientific matters, replied to my 
strictures, ‘‘if chromosomes look equal why are they not equal?’’. 
The words were hardly off the man’s tongue when he saw what 
a remarkable statement he had made. The incident illustrates 
the straits to which one may blindly go in following a theory. 
We conclude this topic with a quotation from John Tyndall. 
In his well-known address on the “‘Scientific Use of the Imagi- 
nation,” he says: 
Let me say here that many of our physiological observers appear to 
form a very inadequate estimate of the distance which separates the 
microscopic from the molecular limit, and that, as a consequence, they 
sometimes employ a phraseology calculated to mislead. When, for 
example, the contents of a cell are described as perfectly homogeneous 
or as absolutely structureless, because the microscope fails to discover 
any structure; or when two structures are pronounced to be without dif- 
ference, because the microscope can discover none, then, I think the mi- 
croscope begins to play a mischievous part. 
In view of the vast amount of evidence now before us from so 
many aspects of biology, that vital processes are periodic in their 
most fundamental manifestations, it appears unwarrantable to 
assume without proof that any whatever are not so.- But see 
what periodicity means; it means that the phenomena are increas- 
