18 
the existing living body. It has established 
a fundamental unity in the organization 
and modes of activity of living things, but 
it has thus far taught us little or nothing 
regarding their origin and progressive trans- 
formations. The interest of the results of 
cell-research, therefore, is of a different kind 
from that attaching to the genealogical 
problems of comparative morphology, and 
the one has grown, in some measure, at 
the expense of the other. 
A no less potent influence has been the 
rapid infusion of experimental methods into 
morphological research, which forms the 
third line of progress in question, and is 
fast becoming the characteristic feature of 
latter-day biology; and with this we may 
briefly regard the far older subject of ex- 
perimental physiology. When we regard 
the novelty and importance of the results 
already attained through these methods, it 
seems strange that morphologists were so 
long content to leave them to the almost 
undisputed monopoly of the physiologists ; 
and I think that zoologists must admit fur- 
ther that, until recently, they have lagged 
behind the botanists in this regard. It 
would; however, be wide of the mark to 
maintain that experimental methods in mor- 
phology are anew product of the day. Did 
not Bacon, in the ‘Novum Organum,’ urge 
that living things are especially adapted for 
experiment, and in the ‘Nova Atlantis’ even 
project a scientific institution for experi- 
mental researches with reference to the 
problem of variation?* More than a cen- 
tury before our time Trembley, Bonnet and 
Spallanzani showed how rich a field lay in 
the experimental study of regeneration ; 
and Darwin later taught us what a wealth 
of suggestive results could be drawn from 
the long-continued experiments of breeders 
of domestic plants andanimals. Neverthe- 
less, it is only very recently that a definite 
program of experimental morphology has 
* Osborn, ‘Greeks to Darwin,’ pp, 92, 93. 
SCIENCE. 
[N. 8. Vou. XIII. No. 314. 
been laidout,and that naturalistshavebegun 
to address themselves seriously to the task. 
The revival of experimental methods in 
morphology is only in part due to a reac- 
tion against genealogical speculation. Itis 
in at least equal measure due—and here we 
touch on a point that is vital to my present 
purpose—to the closer relations that have 
sprung up between morphology and physi- 
ology, and to the development of comparative 
methods on the part of physiologists. Animal 
physiology, long confined almost exclusively 
to the study of vertebrates, at last broke 
away from its earlier traditions and entered 
upon a new career, in the course of which it 
amalgamated with morphology. The tra- 
ditional line between morphology and phys- 
iology thus faded away in zoology, as it 
had earlier done in botany, as naturalists 
advanced from either side into a neutral 
zone of inquiry devoted to the physiology 
of the lower animals and of the cell, to the 
activities of one-celled organisms, and to ex- 
perimental studies on regeneration and de- 
velopment, and on cell-morphology ; while 
in the study of habit, instinct, variation and 
inheritance the psychologist and even the 
sociologist have made common cause with 
us. We may well congratulate ourselves 
on such a solidification of aim and on the 
accompanying increase in the exactness and 
order of our method, and this not merely 
because of the value of the results attained, 
but in no less degree through the revival of 
interest in natural history, in the older 
sense of the word, that has accompanied it. 
We see the signs of this revival in many 
directions—in precise and far-reaching in- 
quiries into the habits and instincts of in- 
sects and birds, and the life of animal com- 
munities; in renewed and more accurate 
ecological studies on plants and animals of 
almost every group, in the increasing in- 
terest in systematic zoology and botany, in 
the extended examination of the plankton 
of inland waters and the sea, in the rapid 
