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: Flurothyl seizure thresholds in mice treated neonatally with a single injection of monosodium glutamate ( MSG ) : evaluation of experimental parameters in flurothyl seizure testing .
### Output Text:
<span class="chemical">Flurothyl</span> seizure thresholds in mice treated neonatally with a single injection of <span class="chemical">monosodium glutamate</span> ( <span class="chemical">MSG</span> ) : evaluation of experimental parameters in <span class="chemical">flurothyl</span> seizure testing . 