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: METHOD : Sphincter of Oddi spasm was induced by prostigmine - morphine administration ( 0 . 5 mg prostigmine intramuscularly and 10 mg morphine subcutaneously ) and visualized by quantitative hepatobiliary scintigraphy .
### Output Text:
METHOD : Sphincter of Oddi spasm was induced by <span class="chemical">prostigmine</span> - <span class="chemical">morphine</span> administration ( 0 . 5 mg <span class="chemical">prostigmine</span> intramuscularly and 10 mg <span class="chemical">morphine</span> subcutaneously ) and visualized by quantitative hepatobiliary scintigraphy . 