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: From such experiments there is evidence that characterization and detection of apomorphine - induced activity in rodents critically depends upon the test conditions employed .
### Output Text:
From such experiments there is evidence that characterization and detection of <span class="chemical">apomorphine</span> - induced activity in rodents critically depends upon the test conditions employed . 