194 



Bionomicfi of Crv})lialus abietis 



Unrii'k 



The nutritive chamber at the apex of 

 the egg-tubes is small and apparently seated 

 directly on the oviduct. 



Egg-tubes diminutive, short, not jjro- 

 minent, not separated off into ovarian 

 chambers. 



Bursa copulatrix empty. Gland associ- 

 ated with the receptaculum serainis empty. 



Rll-K 



Nutritive chamber large. 



Egg-tubes long and pointed so as to 

 suggest strings of beads. The egg-chambers 

 increase in size gradually from the nutri- 

 tive chamber to the oviduct. 



Bursa copulatrix and gland associated 

 with receptaculum seminis well filled. 



Fig. 15. Reproductive organs of female C. ahidis after egg-laying (greatly magnified). 



QUESTION OF THE NUMBER OF GENERATIONS IN A YEAR. 



From repeated observations made in the open and from my experi- 

 ments I am convinced that even under the most favourable conditions 

 the occurrence of a double generation in the succession of parents, 

 children and grandchildren within a single year is most unlikelv. 



