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: A majority of the nodules showed a considerable number of peroxisomes and the inductive proliferation of peroxisomes .
### Output Text:
A majority of the nodules showed a considerable number of peroxisomes and the inductive proliferation of peroxisomes . 