[7]

My idea Wollaston & My idea that isolation plays part in preventing crossing, & adapting forms to very same condition, implies that when the in ordinary cases over same great country that the individual wander into each others regions & so cross. I shd expect often nearly destroyed in one spot & then reimmigrated. This cannot be case with many isolated spot plants in England; & then do not become species, I presume only owing to similarity of condition & want of time, or

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[7v]

at C. of Good Hope the same species of Erica must have ranged over whole country. ─ I fancy you might have a set of isolated groups of same species not varying, (if not or too perfectly adapted) if not at used to condition