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: While gentamicin and kanamycin decreased the percentage reabsorption and accumulation of lysozyme after i . v . administration of egg - white lysozyme netilmicin had no effect .
### Output Text:
While <span class="chemical">gentamicin</span> and <span class="chemical">kanamycin</span> decreased the percentage reabsorption and accumulation of lysozyme after i . v . administration of egg - white lysozyme <span class="chemical">netilmicin</span> had no effect . 