104 THE ENTOMOLOGIST. 



6 males and 3 females on May 23rd, 1889. 

 9 males and 3 females on May 25th, 1889. 



7 males and 3 females on May 26tb, 1889. 

 1 male on June 7th, 1889. 



These specimens also are all completely normal ; some of the 

 females are brighter, others more darkly powdered, but all have 

 the usual yellowish ground colour, such as the specimens cap- 

 tured at large exhibit. There is no difference between the speci- 

 mens of lots I. and IL, and consequently the warmth of the 

 incubator was entirely without influence on all these specimens. 

 Only one male differed from all the rest, and he indeed emerged 

 very late, on July 7th ; as this specimen resembles in almost every 

 respect specimens of the summer form of napi, only the tips of the 

 wings are a little darker than with these. 



Fourth experiment witJi bryonies, — In June, 1889, also I 

 received once more a consignment of living females of bryonicBy 

 through the kindness of Pastor Hauri at Davos, and again 

 succeeded in inducing them to lay eggs. The young larvae 

 began to emerge on June 23rd, and I brought them, on their 

 food-plant, the rape, into the heated incubator, especially con- 

 structed for rearing larvae, at 26-31° C. The rearing was going 

 on satisfactorily ; just before pupation, however, the fungoid 

 disease appeared which is often so destructive to our Pieris 

 larva, and which had already interrupted by its ravages my 

 experiments with bryonies in the seventies. About 30 larvae died 

 immediately from it; others, indeed, pupated, but then died. 

 The solitary butterfly which I reared on July 7th almost com- 

 pletely resembled an ordinary summer female of P. napi var. 

 napce, and principally differed from that in the tip of the fore 

 wing being grey instead of black, and by the black powdering of 

 the veins 1 to 4 of the hind wing on the under side towards the 

 margin of the wing. The latter occurs otherwise only in the 

 winter brood of P. napi^ and is especially strongly pronounced 

 with bryonies. 



The fungus epidemic owed, indeed, its destructive power 

 principally to very damp, and at the same time warm, air in the 

 incubator. Unfortunately, I could not repeat the experiment 

 during the year 1889 ; otherwise I should have tried to reduce 

 the dampness of the air, which cannot be entirely dispensed 

 with, to a minimum ; at the same time also to rear the larvae at 

 the ordinary summer temperature, and to first subject the pupae 

 or the larvae about to pupate to the heat of the incubator. 



Results of the experiments with bryonice, — The results of the 

 experiments here described differ in one point from the experi- 

 ments described in the year 1871, in so far as that not one of the 

 pupae then kept at 15-30° C. emerged as 7iapi ; while in each of 

 the new Experiments, II., III. b, and lY., one butterfly was very 



