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: Scopolamine , but not methyl scopolamine ( 1 and 3 mg / kg ) , induced an amnesia as measured by latency and duration parameters .
### Output Text:
<span class="chemical">Scopolamine</span> , but not <span class="chemical">methyl scopolamine</span> ( 1 and 3 mg / kg ) , induced an amnesia as measured by latency and duration parameters . 