Agassiz vs Gray

Louis Agassiz was a zoologist. Asa Gray was a botanist. They were Harvard professors in Darwin's day.

As I have already noted speciation by polyploidy is no problem for plants. Even in animals, variation within chromosomes keeping their number is no problem, but mammalian as well as plant species have differring chromosome numbers. And though slightly decreasing ones might just be feasible, increasing ones is a major problem if not an outright impossibility. I do not reckon there is a real feasible possibility for it. This message as well as this one deal with it.

You have guessed it, Louis Agassiz being a zoologist was anti-Darwin, his arguments are reused by Creationists to this day. Asa Gray, being a botanist was pro-Darwin.

Subsequent major Darwinists in the following decades were more Lamarckist than purely Darwinist not to mention Darwinist Mendelian. They did not come up as much with good explanations, as with mere discoveries -- I think the Dinosaurs were dealt with back then. Though their discoveries bolstered an impression of "once the fauna was different, so probably fauna, including its details the species has evolved", in explanatory and theoretical terms, they did not dare be fully Darwinist. Leaning too much on environment natural selection and adaption edge of the pair natural selection vs variation as they did is in reality saying, as Lamarck did, that adaptions made with a goal during an animals lifetime can be genetically transmitted. Which is an explanation that heredity has blown to pieces.

HGL