1893. PAE RECAPITULATION THEORY. 281 
the same species, did not investigation of their ontogeny reveal stages 
resembling the adults of pre-existing species belonging to the two 
different genera. In these cases, it is the earliest stages that differ 
most and afford the best proof not only as to their affinities with con- 
temporary species, but as to their perished ancestry. It would be 
rash for one who is no entomologist to hint that the resemblance of 
the adult Culex, Corethva, and Chivonomus is a similar case of con- 
vergence; but it is clear in the case of Dumortieria and Grammoceras 
that “variation” apparently “affecting chiefly the structure of the 
individual in early stages of development ” has actually preserved to 
us a record of the ontogeny. 
Another mistake of Mr. Hurst, is his refusal to admit more than 
one method of variation. He appears to deny that variation occurs 
at the close of ontogeny; if an adult structure varies, he says in 
effect, it ceases to exist as an adult structure at all. It does even- 
tually do so, no doubt, but not immediately. The very same ‘“‘ change 
in the constitution of successive generations of a species leading to 
the production of a new species” does take place in the life-history 
of a single generation. Ontogeny, in fact, forecasts phylogeny just 
as much as it repeats it. An Ammonite that is smooth in the adult, 
will become ribbed in old age; this change takes place at earlier and 
earlier periods in successive generations, till at last a form is attained 
that has ribs in the adult. Then we call it a new species. But this 
new species is spinous in its old age; gradually do the spines, in like 
manner, appear sooner and sooner, till another species, that bears 
spines inits maturity, is found inthe rocks. A similar case is the ten- 
dency of modern civilised man to adopt baldness as an adult 
character, although one that has hitherto been regarded as purely 
senile. Yet all these well-known instances of variation (and I use 
the term precisely in Mr. Hurst’s own sense) ‘“‘ occur in a way utterly 
unlike the way in which it does actually occur,” 7.e., within Mr. Hurst’s 
horizon. Of course, this is not the only method of variation; there 
are sports of differing degrees, and there is variation produced by 
sexual mixture of different strains. If these alone were to be con- 
sidered, we might, of course, be led to different conclusions, that is, 
if we were persistently to shut our eyes to the plain facts of 
paleontology. 
The fact that absurdities and contradictions have arisen from too 
zealous following of the Recapitulation Theory does not actually 
prove the conception false; nor, on the other hand, does the fact 
that under its guidance we have made remarkable discoveries and 
initiated fruitful investigations necessarily prove its truth; at the 
same time, it might possibly lead Mr. Hurst to reconsider his con- 
demnation if he were to make himself acquainted with the brilliant 
researches of Hyatt and Buckman on Cephalopoda, R. T. Jackson on 
Pelecypoda, and Beecher on Brachiopoda, not to mention many 
writings in other tongues than our own, all which works have been 
inspired by the Recapitulation Theory. Th, Avene 
