280 



The Nature of Biological Diversity 





PLATE III. FIGS. 16 to 19 show the mass migration and progressive differentiation 

 of the Purkinje cells in the cerebellum of embryos at 8, 11, 14, and 19 days of 

 incubation. See explanation in the text. 



nevelopmental pattern oi sensory ganglia 

 under normal and experimental eonditions 



In 1934 and in 1939 Hamburger performed the first detailed analysis 

 of the growth and differentiation of sensory ganglia in chick embryos 

 under normal conditions and under the experimental conditions of 

 unloading or overloading their peripheral field of innervation (29, 

 30) . The extirpation of the limb bud at the stage of 3 days of incuba- 



