i8/6.] Biological Controversy and its Laws. 209 
doctrine of Natural Selection must be to supersede it by 
some better hypothesis, just as the “ emission theory ” of 
light was refuted by the production of the “ unaulatory 
theory.” What, therefore, does Mr. Mivart bring forward 
to account for the genesis of species ? We will take his 
own words : — “ It is quite conceivable that the material 
organic world may be so constituted that the simultaneous 
aCtion upon it of all known forces — mechanical, physical, 
chemical, magnetic, terrestrial, and cosmical,* together with 
other as yet unknown forces — which probably exist, may re- 
sult in changes which are harmonious and symmetrical ; just 
as the internal nature of vibrating plates causes particles of 
sand scattered over them to assume definite and symmetrical 
figures when made to oscillate in different ways by the bow 
of a violin being drawn along their edges. The results of 
these combined internal powers and external influences might 
be represented under the symbols of complex series of vibra- 
tions (analogous to those of sound or light), forming a most 
complex harmony or a display of most varied colours. In 
such a way the reparation of local injuries might be sym- 
bolised as a filling up and completion of an interrupted 
rhythm. Thus, also, monstrous aberrations from typical 
structure might correspond to a discord, and sterility from 
crossing with the darkness resulting from the interference of 
waves of light. 
“ Such symbolism will harmonise with the peculiar repro- 
duction of heads in the body of certain annelids, with the 
faCts of serial homology as well as those of bilateral and 
vertical symmetry. Also, as the atoms (?) of a resonant 
body may be made to give out sound by the juxtaposition of 
a tuning-fork, so it is conceivable that the physiological 
units of a living organism may be so influenced by sur- 
rounding conditions (organic and other) that the accumulation 
of these conditions may upset the previous rhythm of such 
units, producing modifications in them, —a fresh chord in 
the harmony of Nature,— a new species. 
Elsewhere he informs us that species arise in virtue of an 
u internal force or tendency,” manifesting themselves “with 
suddenness, and by modifications appearing at once.” 
Mr. Mivart therefore does not, with Cuvier and the ortho- 
dox naturalists of the old school, maintain that every kind 
of animal and plant has been separately formed by a distinct 
* It is interesting to note the case of “ cross division ” presented to the 
reader in this enumeration of forces. 
VOL. VI. (N.S.) 2 A 
