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 : No lymphocyte proliferation was observed either in the patient or in the healthy volunteer in the presence of dilevalol solutions .
### Output Text:
RESULTS : No lymphocyte proliferation was observed either in the patient or in the healthy volunteer in the presence of <span class="chemical">dilevalol</span> solutions . 