Edward R. Speyer 



177 



The late autumn generations were more closely studied in 1913 at 

 Oxford, and the observations made show that differences of temperature, 

 whether applied to the trees, to the individual insects, or to the eggs 

 during oviposition, probably do not affect the resulting proportions of 

 this generation, and certainly not to any appreciable extent. 



The great preponderance of larvae of the Progrediens type produced 

 by the last generation of the year shows the assumption that only 

 Sistentes hatch from the eggs to be completely false. 



It may be noted that a continued exposure to a warm temperature 

 causes a great diminution in the number of eggs laid, and, if climate 

 plays any part at all, this seems to be the only direction in which any 

 effect is produced. 



Finally it is suggested that the sap-flow in the plant, and therefore 

 nutrition of the insect in all stages, may well be a prominent determining 

 feature in the production of Progredientes and Sistentes, in addition to 

 the alternative generations from which they may primarily arise. 



