In the tutorial 'Harnessing the Power of Stigmergy' in the 'Research' section, agents are likened to genes because they provide people with new abilities and functions. Here is an article from the nationalgeographic,com Web site, which describes how a jellyfish gene is transferred into mice. This is exactly analogous to the way in which stigmergic agents empower visitors to a stigmergic system Web site, enabling them to interact with the system.
The article 'Evolving Web sites', also in the 'Research' section, describes how the developmental progress of sites created with a "Web site creator program" can be combined using agents to transfer code modules. This strategy is also based upon the technique of "Horizontal gene tranfer', which is nicely described in the article Report on horizontal gene transfer by Mae-Wan Ho, Reader in Biology at the Open University.