Final answer:
The four pronouns being used as adjectives in the sentence are 'any, remarkable, this, and this'.
Step-by-step explanation:
In the sentence "When we see any part or organ developed in a remarkable degree or manner in any species, the fair presumption is that it is of high importance to that species; nevertheless, the part in this case is eminently liable to variation," the four pronouns being used as adjectives are any, remarkable, this, and this.