The morphic fields include all kinds of organizing fields...: The organizing fields of animal and human behaviour, of social and cultural systems, and of mental activity can all be regarded as morphic fields which contain an inherent memory.
The idea is that there is a kind of memory in nature. Each kind of thing has a collective memory. So, take a squirrel living in New York now. That squirrel is being influenced by all past squirrels.
The cumulative nature of the evolutionary process, the fact that memory is preserved, means that life grows not just through a random proliferation of new forms, but there's a kind of cumulative quality.