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 subcutaneous administration of 10 mg / kg of morphine - HC1 produced a marked increase in locomotor activity in mice .
### Output Text:
The subcutaneous administration of 10 mg / kg of <span class="chemical">morphine</span> - HC1 produced a marked increase in locomotor activity in mice . 