Lets see, The author wants to say that the constraints on how an embryo can be grown will affect what possible phenotypes are actualised. Well that seems plausible enough, I would be interesting in finding out more about HOW to actually grow an embryo? why cant you grow a wheel and axle? But the author doesn't know, too bad. All he can do is talk about how English he is and how great is its to be English and that development must have _somthing_ to do with evolution, Oh and by they way the author is English.