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: QTLs for susceptibility to pilocarpine - induced seizures , a model of temporal lobe epilepsy , have not been reported , and CSS have not previously been used to localize seizure susceptibility genes .
### Output Text:
QTLs for susceptibility to <span class="chemical">pilocarpine</span> - induced seizures , a model of temporal lobe epilepsy , have not been reported , and CSS have not previously been used to localize seizure susceptibility genes . 