42 A JOURNEY IN BRAZIL. 
ever of the whole animal kingdom, whether Radiate, Mol- 
lusk, Articulate, or Vertebrate, before reaching its adult 
condition and assuming the permanent characters which dis- 
tinguish it from other species, and have never been known to 
vary, passes in a comparatively short period through an ex- 
traordinary transformation, the successive phases of which 
differ far more from each other than do the adult species. 
In other words, the same individual differs more from him- 
self in successive stages of his growth than he does in his 
adult condition from kindred species of the same genus. 
The conclusion seems inevitable, that, if the slight differ- 
ences which distinguish species were not inherent, and if 
the phases through which every individual has to pass were 
not the appointed means to reach that end, themselves in- 
variable, there would be ever-recurring deviations from the 
normal types. Every naturalist knows that this is not the 
case. All the deviations known to us are monstrosities, and 
the occurrence of these, under disturbing influences, are to 
my mind only additional evidence of the fixity of species. 
The extreme deviations obtained in domesticity are secured, 
as is well known, at the expense of the typical characters, 
and end usually in the production of sterile individuals. 
All such facts seem to show that so-called varieties or 
breeds, far from indicating the beginning of new; types, or 
the initiating of incipient species, only point out the range 
of flexibility in types which in their essence are invariable. 
" In the discussion of the development theory in its pres- 
ent form, a great deal is said of the imperfection of the 
geological record. But it seems to me that, however frag- 
mentary our knowledge of geology, its incompleteness does 
not invalidate certain important points in the evidence. It 
is well known that the crust of our earth is divided into a 
