12 REPORT—1899. 
other, like dissolving views, all so ordained that often the final shape 
with which the creature seems to begin, or is said to begin, its life in the 
world is the outcome of many shapes, clothed with which it has in turn 
lived many lives before its seeming birth. 
All or nearly all the exact, knowledge of the laboured way in which each 
living creature puts on its proper shape and structure is the heritage of 
the present century. Although the way in which the chick is moulded in 
the egg was not wholly unknown even to the ancients, and in later years 
had been told, first in the sixteenth century by Fabricius, then in the seven- 
teenth century in a more clear and striking manner by the great Italian 
naturalist Malpighi, the teaching thus offered had been neglected or 
misinterpreted. At the close of the eighteenth century the dominant 
view was that in the making of a creature out of the egg there was no 
putting on of wholly new parts, no epigenesis. It was taught that the 
entire creature lay hidden in the egg, hidden by reason of the very trans- 
parency of its substance, lay ready-made but folded up, as it were, and 
that the process of development within the egg or within the womb was 
a mere unfolding, a simple evolution. Nor did men shrink from accepting 
the logical outcome of such a view—namely, that within the unborn 
creature itself lay in like manner, hidden and folded up, its offspring also, 
and within that again its offspring in turn, after the fashion of a 
cluster of ivory balls carved by Chinese hands, one within the other. 
This was no fantastic view put forward by an imaginative dreamer ; it 
was sericusly held by sober men, even by men like the illustrious Haller, 
in spite of their recognising that as the chick grew in the egg some 
changes of form took place. Though so early as the middle of the 
eighteenth century Friedrich Caspar Wolff and, later on, others had 
strenuously opposed such a view, it held its own not only to the close 
of the century, but far on into the next. It was not until a quarter 
of the present century had been added to the past that Von Baer made 
known the results of researches which once and for all swept away the 
old view. He and others working after him made it clear that each 
individual puts on its final form and structure not by an unfolding of 
pre-existing hidden features, but by the formation of new parts through 
the continued differentiation of a primitively simple material. It was 
also made clear that the successive changes which the embryo undergoes 
in its progress from the ovum to maturity are the expression of 
morphologic laws, that the progress is one from the general to the special, 
and that the shifting scenes cf embryonic life are hints and tokens of lives 
lived by ancestors in times long past. 
If we wish to measure how far off in biologic thought the end of the 
last century stands, not only from the end but even from the middle of 
this one, we may imagine Darwin striving to write the ‘Origin of 
Species’ in 1799. We may fancy him being told by philosophers that one 
group of living beings differed from another group because all its members 
