



PLATE I. 



Fig. 1. Leptinotarsa undecimlineata, normal form. 



Fig. 2. Form derived from L. undecimlineata through the application of the 

 climatic conditions. For convenience this form has been called angiistovittata be- 

 cause it most closely resembles a species described by Jacoby, but it differs from 

 anijnstovittata in many characters considered important by the pystematists. 

 [From Plate 16, Investigation of Evolution in Chrysomelid Beetles of the genus 

 Leptinotarsa. Carnegie Institution, Publication No. 48, 1903. After Tower.] 



Figs. 3, 4. Normal mitosis of nuclei in cells of plant. 



Figs. 5, G, 7, 8. Irregularities of mitosis in cells of onion roots resulting from 

 exposure to radium. [After Gager. j 



