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: Long - term oral galactose treatment prevents cognitive deficits in male Wistar rats treated intracerebroventricularly with streptozotocin .
### Output Text:
Long - term oral <span class="chemical">galactose</span> treatment prevents cognitive deficits in male Wistar rats treated intracerebroventricularly with <span class="chemical">streptozotocin</span> . 