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: An electrical seizure measured with hippocampal EEG appeared in the pilocarpine - treated group .
### Output Text:
An electrical seizure measured with hippocampal EEG appeared in the <span class="chemical">pilocarpine</span> - treated group . 