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: These results are consistent with the hypothesis that the rat has a poorer tolerance for deoxycholic acid than do certain other species .
### Output Text:
These results are consistent with the hypothesis that the rat has a poorer tolerance for <span class="chemical">deoxycholic acid</span> than do certain other species . 