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: All animals suffered tonic convulsions at 18 . 3 + / - 1 . 4 min after lindane administration .
### Output Text:
All animals suffered tonic convulsions at 18 . 3 + / - 1 . 4 min after <span class="chemical">lindane</span> administration . 