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: The effect of high dose D - penicillamine treatment on aortic permeability to albumin and on the ultrastructure of the vessel .
### Output Text:
The effect of high dose <span class="chemical">D - penicillamine</span> treatment on aortic permeability to albumin and on the ultrastructure of the vessel . 