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: 10 monkeys ( macaques ) received adriamycin by monthly intravenous injections at 12 mg / m2 ( 1 mg / kg ) .
### Output Text:
10 monkeys ( macaques ) received <span class="chemical">adriamycin</span> by monthly intravenous injections at 12 mg / m2 ( 1 mg / kg ) . 