Developmental Processes and Their Regulation

Cell elongation is a quite simple process of differentiation. In the next few chapters we shall consider in some detail a few complex developmental processes which consist of a large number of individual processes which interlock with each other. Longitudinal growth also participates in these developmental processes but only as one component among many. 

We cannot deal here with all of the developmental processes that could be the starting points for a causal analysis, quite apart from the fact that only a very few facts are known about some morphogeneses. In view of the need to be selective it seems desirable that we be guided by the following criteria  

Now transitions of decisive importance are those from dormancy to activity (and vice versa) and those from the vegetative to the reproductive phase of development. Transitions from dormancy to activity are found, for example, in the forcing of side buds and in germination. The transition from the vegetative to the reproductive phase of development in higher plants proceeds with the formation of flowers. The dormancy and activity of side buds has already been mentioned once or twice (pages 198, 202). Thus we shall concentrate here on germination and flower formation. 

These points fix our agenda we shall discuss, in the order shown  

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