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: CONCLUSION : There is an age - related pupillary response to pilocarpine that is not found with tropicamide .
### Output Text:
CONCLUSION : There is an age - related pupillary response to <span class="chemical">pilocarpine</span> that is not found with <span class="chemical">tropicamide</span> . 