ABSTRACT
Development seems to occur in a stepwise fashion, the completion of each step setting the stage for the next. Each step may be comparatively simple, even if the end result of a long sequence of such steps is exceedingly complicated. This chapter discusses what kinds of ‘counting machine’ could exist, and then ask to which kind embryos belong. Strictly, such machines ought to be called ‘number generating machines’, and the phrase ‘counting machines’ should be reserved for those which can do something a variable number of times or which respond in qualitatively different ways according to the number of times they have been stimulated. In digital counting, the ‘machine’ must again be able to generate discrete events, but the number of events is regulated by pairing them off one by one with a pre-existing set of entities contained in the machine.
