18 
flies that emerged from this lot were com- 
pletely changed, being telamonides and 
walshii, and about half the rest were partly 
changed. It was observed also that the 
butterflies were generally smaller than the 
average marcellus. Ihave not been able 
to subject chrysalids to cold fora very long 
period, for the reason that ice fails us in 
midsummer, it having been put up when 
thin and of poor quality, owing to our 
moderate winter climate. Indeed, in some 
seasons we get no ice at all, as the streams 
do not freeze over. On more than one 
occasion the period of exposure has abruptly 
terminated, and much earlier than I had 
intended, by the failure of the ice. 
SUMMARY OF THE EXPERIMENTS WITH 
P. ajax. 
In 1877: chrysalids 1 to 3 hours old 
exposed from 23 to 8 days. ‘Temperature 
33°+ F. [0.6° C.]. No change effected. 
In 1878: chrysalids 10 to 15 minutes 
old, and at intervals up to 1 day, and then 
daily to 8th day from pupation; expos- 
ure from 19 to 5 days. Result: one 
telamonides or walshii from chrysalis 12 
hours old, 11 days exposure ; one walshii 
from chrysalis 2 hours old, 11 days expos- 
ure ; one telamonides from chrysalis 3 days 
old, 16 days exposure; all the rest un- 
changed, but the periods of emergence 
remarkably prolonged. Temperature 33° 
S 2. poo” C.}. 
In 1879: chrysalids not less than 12 
hours old nor over 24 hours; exposed 14, 
20, and 24 days. Result: the period of 
emerging greatly precipitated in nearly all 
cases. From the 14-day lot there was no 
change or only a partial one ; from the 20- 
day lot, one half were changed, the rest 
PSYCHE. 
partly or not at all; from the 25-day lot 
all were changed. Temperature 33°+ F. 
fOx6 Cal: 
In 1877: chrysalids under 12 hours old, 
but the minimum not noted; exposure 24 
days. Temperature 40° F. [4.4° C.] and 
upwards, irregular. Result: one changed 
fully, seven partly ; some others subjected 
to same conditions for 23 days were fully 
changed ; others at 26 days not at all. 
In 1875: chrysalids stated in my note 
book to have been exposed ‘‘as formed,” 
but the exact age not given; exposed for 
30 to 60 days; temperature at first about 
32° F. [0° C.], afterwards uncertain. Re- 
sult: 50 per cent. fully changed, 25 per 
cent. partly, rest not. 
GENERAL CONCLUSIONS : — 
1. P.ajax. The longer the exposure 
under a low temperature the more decided 
the change, but 25 or 30 days seem quite 
sufficient in many cases, and changes have 
been produced by exposure for 20, 16 and 
11 days; no changes recorded at less than 
11 days ; while exposure at 8 days and less 
has produced no effect except in some cases 
to prolong the chrysalis period. 
2. The longest interval between pupa- 
tion and exposure to cold when any change 
has resulted, has been 3 days. In all in- 
stances beyond that no change has been 
produced. The shortest interval has been 
two hours, and in this instance the but- 
terfly was changed to walshiti, which is a 
change more extreme than to telamonides. 
Most chrysalids exposed so early die in the 
process, but as many changes have been 
effected when the age of the chrysalis at 
exposure has been from 12 to 24 hours, I 
believe that to be the most satisfactory pe- 
riod. The chrysalis has then become hard- 
