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: A transient tonic pupillary response , denervation supersensitivity , and abnormal visual - evoked potentials in quinine toxicity , to our knowledge , have not been previously reported .
### Output Text:
A transient tonic pupillary response , denervation supersensitivity , and abnormal visual - evoked potentials in <span class="chemical">quinine</span> toxicity , to our knowledge , have not been previously reported . 