814 



Scientific Proceedings^ Royal Dublin Society. 



Before one can investigate the influence of external factors on production 

 of winged forms, it is necessary to estimate by extensive breeding experi- 

 ments the extent and relations of this inherent tendency to vying-production 



BEANS 



Months 



IV 

 IV 

 V 

 V 

 VI 

 VI 



\ai 

 vn 

 vin 



K 

 X 

 X 



XI 



xn 



I 



n 



n 



m 



Fig. 3. 



Illustrating, in successive generations of A. rumicis, tlie appearance of winged and apterous 

 forms, also of sexual forms, on Broad Beans and Euonymus. The months are shown at the right- 

 hand side. The series is being continued. 



^ Fundatrices. • Apterous viviparous females. O Winged viviparous females. "Winged 

 sexuparae. ? Sexual females, s Males. 



in different agamic females. It is generally considered that the winged 

 condition is the more primitive, and that the apterous condition has arisen 



