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: Tonic - clonic seizures followed intravenous fluorescein injection for fundus angiography in a 47 - year - old male .
### Output Text:
Tonic - clonic seizures followed intravenous <span class="chemical">fluorescein</span> injection for fundus angiography in a 47 - year - old male . 