( xcv ) 



2nd April and 7th May. It will be seen by the tables in the 

 Appendix that all those transferred to the incubators in less 

 than 13 (perhaps 15) weeks after pupation died; after that a 

 proportion died, gradually diminishing until the 29th week, 

 after which all survived. 



A large number during the first eight weeks were left in 

 the room at a temperature which may be taken at 5°-10° F. 

 (3°-6° C.) above that of outdoors. These were afterwards 

 transferred in batches to the incubators. All so transferred 

 up to the 19th week died ; after which a proportion, gradually, 

 but irregularly, increasing, but never the whole of those 

 transferred, survived.* (Of some left in the room until 

 emergence, 23 emerged between 24th March and 31st May.) 



Of a tbird lot left in the room until 13th January (19 weeks), 

 when they were placed out of doors and from 7th February 

 (24 weeks) transferred as before to incubators, some of each 

 batch transferred survived, the proportion being larger than 

 in the last experiment.! (Some of them, left out of doors 

 from the time they were placed there, emerged, to the number 

 of about 20, between 26th April and 19th May.) 



Experiments with other seasonal double-brooded species 

 show an equal resistance to a heightened temperature on the 

 part of the winter phase. Thus, of 40 English pupae of P. 

 brassier forced at 80° F. (27° C.) from the 29th November, 

 1897, all but 7 were dead by 23rd March, 5 more by 18th April, 

 the remaining 2 on 22nd May, one of these last in attempting 

 to emerge. Eighteen of the same batch were iced 29th Novem- 

 ber, and forced on the 23rd March; 11 of these emerged 

 between the 3rd and 6th April. Another lot of 36, received on 

 the 30th December, 1900, were kept out of doors ; of 10 forced 

 1st March only one emerged, on 21st March ; of 6 forced 

 19th April only 2 emerged, on 30th April ; of 6 kept outdoors 

 all emerged from 30th May to 2nd June. 



Many experiments tried by me on Selenia tetralunaria, some 

 of which are recorded in the Transactions and Proceedings 

 of this Society, show somewhat similar results. As to the 

 summer phase of this species, when the pupa is forced at about 



* See Table II in Appendix, Experiment 2. 

 t Ibid., Experiment 3. 



