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: Given the marked degree of efficacy of subcutaneous apomorphine treatment in fluctuating Parkinson ' s disease , this approach seems to deserve more widespread clinical use .
### Output Text:
Given the marked degree of efficacy of subcutaneous <span class="chemical">apomorphine</span> treatment in fluctuating Parkinson ' s disease , this approach seems to deserve more widespread clinical use . 