The practice of using a ‘normal development’ is central to experimental work in developmental biology.

There are multiple ways in which development can be normal, and these centre on the management of variation.

I provide a case study of normal development in early experimental embryological research by Edmund Beecher Wilson.

Wilson's normal development exhibited distinctive practices, purposes and results of the abstraction of variation.

I suggest considering normal development as a technical condition in a Rheinbergian experimental systems framework.