16 



COLORATION IN POLISTES. 



closer adherence to this type pattern than the males. This fact was 

 long ago attested by De Saussure. 



NATURE OF THE VARIATION IN A SINGLE NEST. 



Another question which naturally arises is, To what extent do the 

 members of a single colony participate in the whole range of variation ? 

 Do the different series of transitions correspond in any manner with 



FIG. 8. Diagrammatic representation of the proportion of males to females in the types of color 

 pattern found in collections of southeastern Wisconsin. The shaded portions repre- 

 sent the males, the unshaded portions the females. The relative position of classes 

 is the same as in fig. 7. From this it will be seen that the males tend to the extreme 

 conditions both for the xanthic and melanic types. Proceeding in any direction from 

 the modal condition the proportion of males tends to increase, while the proportion 

 of females tends to decrease. 



the condition in particular colonies, and the species thus fall into a 

 number of definite races, determined by the particular markings of 

 their progenitors or peculiar local conditions of their surroundings ? 



