Where does germ collide?

In mathematics, the germ of a function or mapping at a point is the equivalence class of all maps that agree with it on some arbitrarily small neighbourhood of that point, discarding everything except the map's purely local behaviour there. This is exactly the object singularity theory needs to classify how a map behaves near a point, and Golubitsky and Guillemin's Stable mappings and their singularities works throughout with germs. The referent is a local object in analysis and geometry, nothing to do with a microbe or a reproductive cell.[1]

Unit

The local equivalence class of a map at a point

Recovery means

Not applicable

Measured by

Identified up to agreement on some neighbourhood, and classified by its local normal form

In developmental biology, the germ line (and its germ cells) is the lineage of cells set aside early in development that will give rise to eggs and sperm, kept distinct from the body's somatic cells so that only changes in the germ line are passed to offspring. Gilbert's Developmental biology traces how germ cells are specified and migrate to the gonad. The referent is a reproductive cell lineage, a wholly different thing from a pathogen or a mathematical germ.[2]

Unit

The lineage of cells committed to producing gametes

Recovery means

Not applicable

Measured by

Identified by germ-cell markers and traced by lineage from their specification to the gonad