==Darwin explains that each capital letter represents species of a widespread genus
Hypothetical, no data
==that each horizontal line represents a thousand generations (or even better, 10,000)
Hypothetical, no data
==and that each small letter-number combination represents a new variant in the species
Hypothetical, no data
That’s not what “hypothetical” means. Do you believe there are such things as genera, species, and generations? Then saying “let this line represent a thousand generations” is not hypothetical.
I repeat, can you do even that much with the degeneration chart?