What if Huxley performed Mendel's pea plant crossbreeding or similar experiments and disproved blending inheritance? Since the prevailing idea of blending inheritance was one of the major blocks to early acceptance of evolution and natural selection (and something Darwin struggled with explaining), how would this affect the overall acceptance of the theory of evolution and how would it impact the direction of the field of biology?
Why would he? He's not a breeder of anything, right? Why peas? Gregor Mendel was a monk in a monastery growing peas, and looked at what they were growing, and played with crossing and back crossing.
I think you'd be far more likely to get some other, random unknown breeding something (whatever they were breeding) and getting interesting results. You'd have to be breeding creatures that DON'T mostly blend to be able to do this. Mendel was lucky that most of the qualities he looked at were binary - two alleles with few modifying factors. He would not have gotten such clear results if he'd tried most other organisms.
So why on earth would Huxley pick peas?
Even with Mendel himself, he then tried Hawkweed which reproduces both sexually and asexually and totally mucks up the 'rules'.