Sentence:  The sections were mounted on cold <WSD>slides</WSD> smeared with Haupts ' adhesive ( Johansen , 1940 ) in earlier experiments , and in later experiments with a different mixture of the same components reported by Schramm and Rottger ( 1959 ) . 
Meaning of the word marked with <WSD> tags:  a small flat rectangular piece of glass on which specimens can be mounted for microscopic study