In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: RESULTS : It was found out that crocin ( 30 mg / kg ) - treated STZ - injected rats show higher correct choices and lower errors in Y - maze than vehicle - treated STZ - injected rats .
### Output Text:
RESULTS : It was found out that <span class="chemical">crocin</span> ( 30 mg / kg ) - treated <span class="chemical">STZ</span> - injected rats show higher correct choices and lower errors in Y - maze than vehicle - treated <span class="chemical">STZ</span> - injected rats . 