JANUARY 4, 1901.] 
It will be worth our while to inquire into 
the reasons for this. 
First, we cannot repress a certain feeling 
of dissatisfaction at the vagueness of our 
conclusions regarding many of these major ~ 
problems. Our knowledge of the anatomy 
and development of the leading types of 
life is still very far from complete—indeed, 
the field before us remains so vast that we 
may never hope to exhaust its possibilities 
of research. We have, nevertheless, gained 
a fairly clear view of the general outlines 
of the system. But have we reached sub- 
stantial agreement regarding the natural 
affinities of the great types? In a few cases, 
yes ; but I think the candid naturalist must 
also reply, in most cases, no. How is it 
with that time-honored problem, the origin 
of vertebrates, in one way the most inter- 
esting of all, involving as it does our own 
remote ancestry ? How is it with the ori- 
gin of annelids or mollusks, of echinoderms, 
of platodes, of round worms or molluscoids ? 
What are the historical relationships of the 
higher types to the Ceelenterata, of bilateral 
to radial forms, or of Metazoa to Protozoa? 
I dare say most of the morphologists pres- 
ent hold more or less definite views on 
these questions—if I, for one, am charged 
with holding such views on the zoological 
side I shall not defend myself or deny that 
all these are questions of high interest to 
me. But have we reached definite conelu- 
sions on which we are substantially agreed ? 
I fear that a general discussion of the zoo- 
logical members of this society would elicit 
but too emphatic a negative reply, and that 
a similar symposium of our botanical breth- 
ren would not set us a better example 
of unanimity. I do not doubt that the 
progress of research will in time bring us 
much nearer to a definite solution of these 
great problems; though it lies in the na- 
ture of the case, that we can never attain 
complete certainty. In the mean time, we 
may as well admit that in the application 
SCIENCE. 
li 
of the embryological evidence to the broader 
problems of descent the recapitulation the- 
ory has encountered so many difficulties, 
undergone so many modifications and lim- 
itations, that investigators have in a meas- 
ure wearied of their wanderings through the 
scholastic mazes of ancestral and secondary 
characters, of palingenesis and cenogenesis, 
of primary and adaptive forms and the like, 
and have sought for new interests and 
fresh motives of study. This is clearly 
apparent in the changed character of the 
more recent papers in embryology, which 
devote far less attention than those of ten 
or’ fifteen years ago to ‘genealogische Be- 
trachtungen ’ that once formed their inev- 
itable climax. The relative decline of in- 
terest in genealogical questions is partly 
due, I think, to a healthy reaction against 
the inflated speculation into which morphol- 
ogists have too often allowed themselves 
to fall; but it is also in large measure a re- 
sult of the growing feeling that the solution 
of the broader problems of genealogy still 
lies so far beyond our reach that we would 
better turn for a time to the study of ques- 
tions that lie nearer at hand and are, to say 
the least, of equal interest and importance. 
We here arrive at a consideration of the 
two other great lines of progress to which 
I have referred. The first of these includes 
the modern developments of the cell theory, 
which have perhaps contributed equally 
with the evolution theory to the unification 
of biological knowledge. I need not dwell 
on the fundamental importance or the fas- 
cinating interest of the general results that 
have been attained in this field. The point 
on which I would lay emphasis is that in- 
vestigation in this direction has only in 
very minor degree been inspired by the 
evolution theory or influenced by the his- 
torical point of view. The study of the 
cell, whether morphological or physiolog- 
ical, has been inspired by the desire to pene- 
trate more deeply into the mechanism of 
