Figure 1.

Illustration of Weismann’s vital units. Each chromosome, or idant (A), is composed of several ids (dark blue) (B) that are inherited intact from the parental germ cells within the germ plasm. Each id is composed of determinants (C) that are arranged in a particular architecture. Each determinant corresponds to a specific cell type in an organism and contains a particular assemblage of biophors (D), a group of molecules that, when released from the nucleus and into the cytoplasm, provide the starting material from which cellular components develop.