On Aquatic Carnivorous Coleoptera or Dytiscide. 189 
far reaching and enduring law—the transition must have been long enduring in 
time and wide spread in space. Can we believe it possible that universal law 
should have resulted in the production of a single inconceivably minute portion of 
organic matter, from which all the enormous aggregate of organisms now around 
us has been produced in its almost unthinkable variety by a process of simple 
reproduction? No, I think that whatever the mode or modes may have been by 
which inorganic matter became organic, it will surely prove more credible that 
the passage extended over a vast period of time, and occurred in numerous places, 
and was not limited to one instant of time and a single pin point of space. If 
we say this we admit that it is possible that there have existed distinctions in 
the individual masses of organic beings from their very beginnings, and it is 
quite conceivable that in these aboriginal molecular differences may have 
originated the present physiological species distinctions,—that these are in tact 
absolute and direct continuations of primeval molecular differences of constitution ; 
and it is credible that from such a myriad beginning, through the enormous ages 
of the world there have developed the vast multitudes of species of plants and 
animals amongst which we live. If anything like this has been true, we need 
not necessarily adopt any theory of community of descent, but we may believe 
that each species is a distinct record of the past conditions in which it has existed, 
and that resemblance in structure of two different species is the result of similar 
growth under similar conditions. 
I shall not at present allude farther to the difficulties that surround the theory 
of community of descent, but I may remark that even if it should prove that we 
must abandon the hope of tracing the pedigree of all creatures back to a single 
organism, this in nowise detracts from the importance of biology. We are not 
called on to abandon the attempt to understand the relations between existing 
and extinct morphological forms, species by species, and to trace the road by which 
existing structures have become what we see them. The theory of evolution is in 
no way connected with the hypothesis of common descent; and by means of the 
perfected acquaintance with the structures of existing organisms we shall attain, and 
of the detailed knowledge we shall acquire of the special modifications that have 
taken place in myriad separate lines of descent on various parts of the earth’s 
surface, we may well hope that we shall be able to read slowly but truly the great 
history of Nature. 
Bates has an admirable remark—(“ Naturalist on the Amazons,” Vol. II, p. 345) 
speaking of the local variations in the patterns on the wings of butterflies, he has 
said, “On these expanded membranes Nature writes, as on a tablet, the story of 
the modifications of species, so truly do all changes of the organization register 
themselves thereon.” By the evolutionist this sensitiveness thus truly claimed for 
the butterfly’s wing, may logically be asserted to have always existed in all the 
structures of every species of the organic world. Every individual is a mass of 
‘ 2C2 
