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: Similarly , pre - test scopolamine partially reversed the scopolamine - induced amnesia , but not significantly ; and pre - test cycloheximide failed to reverse the cycloheximide - induced amnesia .
### Output Text:
Similarly , pre - test <span class="chemical">scopolamine</span> partially reversed the <span class="chemical">scopolamine</span> - induced amnesia , but not significantly ; and pre - test <span class="chemical">cycloheximide</span> failed to reverse the <span class="chemical">cycloheximide</span> - induced amnesia . 