COLORATION IN POLISTES. 



II 



sheens of gold and violet playing over the surface of the body and the 

 wings. These are due to structural conditions, and, for the purposes 

 of this research, will be disregarded. 



INDIVIDUAL VARIATION IN THE COLOR PATTERN OF POLISTES. 



Object. — The object of this study was to ascertain : 

 (i) The nature and extent of the variation among individuals of 

 the single colony. 



(2) The relation of this variability to the variability observed in 

 the several species. 



(3) The relation of the variability observed in the single species to 

 the color-differences which constitute specific differences. 



Fig. 5. -Cross-section through cuticle of Polistes pallipes, first abdominal segment of pupa: (a) 

 Hypodermal cells, {b) Cuticle with wavy striations, (c) Channels leading from hypo- 

 dermis to surface. 



Fig. 6.— Cross-section through portion of cuticle, mesothorax of pupa of P. pallipes, showing 

 change in structure of cuticle in passing from a more to a less densely pigmented 

 area: (a) Tactile spine, (6) Pigment deposited in cuticle in form of dense granules 

 (c) Zone of embryonic cuticle, (d) Hypodermis. At the right the granular pigmented 

 area shades off iuto the transparent striated area of cuticle. 



Methods. — The .study of individual variation was made from two 

 classes of material : (i) Specimens collected at random and (2) speci- 

 mens taken directly from the nest. In the latter case the wasps were 

 either anaesthetized on the nests, or the nests were taken into the house 

 and the wasps secured as soon as they emerged from the pupal condi- 

 tion. All were carefully pinned, dried, and labeled in the fashion usual 

 with collectors. The greater part of the variation studies were made 

 on Polistes variatus Cresson ; consequently this species will be consid- 

 ered first and in greatest detail. 



