26. Subject to the provisions of sections 13 and 15, one trustee is not, as such, liable for a breach of trust committed by his co-trustee: Provided that, in the absence of an express declaration to the contrary in the instrument of trust, a trustee is so liable,-(a) where he has delivered trust-property to his co-trustee without seeing to its proper application:(b) where he allows his co-trustee to receive trust-property and fails to make due enquiry as to the co-trustee's dealing therewith or allows him to retain it longer than the circumstances of the case reasonably require:(c) where he becomes aware of a breach of trust committed or intended by his co-trustee, and either actively conceals it or does not within a reasonable time take proper steps to protect the beneficiary's interest.