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: Low doses of pilocarpine caused a pronounced enhancement of the catalepsy that was induced by the dopaminergic blocker , haloperidol .
### Output Text:
Low doses of <span class="chemical">pilocarpine</span> caused a pronounced enhancement of the catalepsy that was induced by the dopaminergic blocker , <span class="chemical">haloperidol</span> . 