SOME PROBLEMS OF COELENTERATE ONTOGENY 529 
it may be made to account for anything and everything. The funda- 
mental assumption that whereas germ-plasm can give rise to body-plasm 
to any extent, body-plasm can under no circumstances give rise to germ- 
plasm, introduces an unnecessary mystery . . . . The fiction 
of two protoplasms, distinct and yet commingled, is in my opinion, lit- 
tle calculated to advance our knowledge of organic processes. 
It has been assumed, as the foregoing citations clearly show, 
that there is some predetermined order of sequence and relation 
as to the origin, nutrition, growth, etc., of germ-cells, not only 
in such a group as the hydrozoa, but throughout the animal 
kingdom. And with this as a postulate assiduous search has been 
directed to its support. It is not necessary that one should, 
a priorv discredit the method, for it is perfectly scientifiec,—within 
limits. The fault which must be emphasized is that it has been 
so conspicuously partial and dogmatic. Facts quite as accessible, 
quite as convincing, have been silently ignored; and it is thus that 
such work or method becomes both unscientific and untrue. I 
believe the foregoing facts must suffice to show that, both as to 
origin, differentiation and growth, the germ-cells of the Hydrozoa, 
so far from sustaining the doctrine of the germ-plasm, afford the 
strongest and most direct evidence to the contrary. 
2. Doctrines of homology 
[f one were asked to indicate the dominant conception which 
characterized the biological activity of the greater part of the 
nineteenth century he could hardly go far amiss in phrasing it 
somewhat as follows: The perennial and irrepressible search for 
homologies! 'This would be confessedly the case with so much of 
the period as comprised the Darwinian epoch of biology. But 
the conception belongs quite as properly to the seething period 
of the biological renaissance of the early half of the century, and 
finds expression in the researches of von Baer and Cuvier, Lam- 
arck and St. Hilaire, and a long roll of hardly less distinguished 
names. But strangely enough the doctrine had antipodal sig- 
nificance under the early, as contrasted with the later epochs of 
thought. To the first homology embodied the postulate of types 
of creation according to the conception of ‘archetypes’ of plan and 
