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: Tacrine , administered in LiCl pre - treated rats , induces electrocorticographic seizures and delayed hippocampal damage .
### Output Text:
<span class="chemical">Tacrine</span> , administered in <span class="chemical">LiCl</span> pre - treated rats , induces electrocorticographic seizures and delayed hippocampal damage . 