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 : The selected doses of WR242511 , which produced significant methemoglobinemia in beagle dogs in earlier studies conducted elsewhere , produced very little MHb ( mean < 2 . 0 % ) in the rhesus monkey .
### Output Text:
RESULTS : The selected doses of <span class="chemical">WR242511</span> , which produced significant methemoglobinemia in beagle dogs in earlier studies conducted elsewhere , produced very little MHb ( mean < 2 . 0 % ) in the rhesus monkey . 