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: Catalepsy was induced by haloperidol ( 2 mg / kg p . o . ) , while apomorphine ( 1 . 5 mg / kg s . c . ) and amphetamine ( 2 mg / kg s . c . ) were used for studying climbing behavior and locomotor activities , respectively .
### Output Text:
Catalepsy was induced by <span class="chemical">haloperidol</span> ( 2 mg / kg p . o . ) , while <span class="chemical">apomorphine</span> ( 1 . 5 mg / kg s . c . ) and <span class="chemical">amphetamine</span> ( 2 mg / kg s . c . ) were used for studying climbing behavior and locomotor activities , respectively . 