A scanning electron micrograph showing the various stages of
transformation of Dictyostelium. Each body represents a different
stage in the process. Hundreds of thousands of single cells
aggregate to form a migrating “slug” (lower left). Once the slug
comes to a stop, it gradually elongates to form the fruiting body.
[Courtesy of M. J. Grimsom & R. L. Blanton, Texas Tech Univer-
The practice of agriculture is not limited to humans: ants, termites, and snails all grow fungi, and who knows who else do something similar. But not many have claimed that such activities are to be found among simpler organisms. Now we have a report that slime molds have also gone down the road to agriculture. Dictyostelium discoideum, the best studied of the cellular slime molds, is a social amoeba that thrives by grazing on bacteria. Given ample bacterial food, these organisms grow as single cells. When food becomes scarce, they aggregate into pretty, differentiated fruiting bodies (called sorus, plural sori) consisting of a round mass of spores held up by a stalk. The spores eventually become dispersed, to repeat the cycle at a new site. The entire epic can be viewed in a dramatic documentary available here. (This movie is narrated in German, giving you the opportunity to hone your skills in that language.)