Chapter VI Difficulties on Theory
“Firstly, why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion instead of the species being, as we see them, well defined?”
“But, as by this theory innumerable transitional forms must have existed, why do we not find them embedded in countless numbers in the crust of the earth?”
“But in the intermediate region, having intermediate conditions of life, why do we not now find
closely-linking intermediate varieties? This difficulty for a long time quite confounded me.”
“Lastly, looking not to any one time, but to all time, if my theory be true, numberless intermediate varieties, linking most closely all the species of the same group together, must assuredly have existed; but the very process of natural selection constantly tends, as has been so often remarked, to exterminate the parent forms and the intermediate links. Consequently evidence of their former existence could be found only amongst fossil remains, which are preserved, as we shall in a future chapter attempt to show, in an extremely imperfect and intermittent record.”
The explanation given is:
“As natural selection acts solely by the preservation of profitable modifications, each new form will tend in a fully-stocked country to take the place of, and finally to exterminate, its own less improved parent or other less-favoured forms with which it comes into competition. Thus extinction and natural selection will, as we have seen, go hand in hand. Hence, if we look at each species as descended from some other unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very
process of formation and perfection of the new form.”
...clearly lacking in that little thing called DETAILS...Darwin did however say that to date (his date) not enough fossil evidence had been found...and according to...Robert L. Carroll:
Patterns and Processes of Vertebrate Evolution, Cambridge University Press, 1997, p. 25.
THEY STILL HAVEN’T...
http://embryology.med.unsw.edu.au/pdf/Origin_of_Species.pdf
They also weren't terribly strong on the Germ Theory of Disease.
The result was a lot of his stuff was mere specualtion.