310 JouRNAL OF COMPARATIVE NEUROLOGY. 
experience. If the new sense presentation is a yellow dog with 
white feet we assimilate it at once with previous experience and 
approve it as a valid fact. If, on the other hand, it is a green 
dog with thirteen scarlet heads each with a forked tongue, we 
are apt to ask, Am I awake or asleep? or, What was I drink- 
ing last night? Such an experience may be vividly real to me, 
but if awake and sane I do not accredit it as an object of sense, 
as a fact of experience, unless I can correlate it with the body 
of fact already approved. 
But scientific laws are merely ‘‘facts’’ of wider import, 
which rest on a foundation of broader experience such that, 
when objectified, they remain not as concrete elementary exper- 
iences but as general categories including many such elements. 
The scientific generalization or law must therefore be approved 
or evaluated in a way strictly analogous with that by which we 
test sense impressions; that is, to be acceptable it must fit in 
harmoniously with the whole content of experience—‘‘it must 
explain all the facts.”’ 
In the solution of any scientific problem that method is 
most likely to lead directly to fruitful results, other things being 
equal, which favors the correlation of the data all along the line 
so that each correlation may become at once a datum for future 
research, instead of reserving the major correlations until near 
the end of the investigation. And in biological research, to 
return to our text, we must not forget for an instant that the 
organism is a functoonmmg mechanism. We cannot hope to un- 
derstand any animal or plant or organ until we have an exhaus- 
tive knowledge of how it works. The anatomical fact is dead 
and inert unless it is vivified not only by the ‘‘salt of morpho- 
logical ideas’? as it was so happily phrased years ago, but also 
by the fresh warm blood of functional explanations. 
Anatomy has given place, within the memory of even the 
younger generation of biologists, to morphology, in which the 
explanation is indissolubly linked with the fact. Nor can we 
stop here. No anatomical fact is complete until its physiolog- 
ical significance is added thereto. Like the old-time descriptive 
anatomist, the ‘‘pure’’ morphologist (or shall we dubb him 
