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: These anticataleptic effects were exhibited dose dependently at doses from 0 . 625 and 2 . 5 mg / kg p . o . , respectively .
### Output Text:
These anticataleptic effects were exhibited dose dependently at doses from 0 . 625 and 2 . 5 mg / kg p . o . , respectively . 