EXPERIMENTS ON VANESSA 10, L. 21 



they take 23-28 clays to develop, while if left in the same conditions 

 as the lai'v^, they emerge in 8-11 days. On the other hand, all 

 "shade" ova, larv^, and pup^e produce var, iitenoulea (as oval and 

 larval form), the pupal stage extending over 26-31 days. Even if the 

 — °pupte from — °ova (1 do not include the " ice " ova of brood IV) 

 and — °larvffi are transferred to hot, sunny cages they will not produce 

 var. teloides unless they are transferred within a da<i or so after 

 pupation. If exposed to heat later — or if only so exposed to an 

 insufficient degree — they emerge with perhaps a darkened ground 

 colour as ab. inesoides-brnnnea. Similarly, the pupfe from -|-°ova and 

 larvfe produce var. mewides — and beyond that even the protoid ab. 

 fischeri — but only //" they are directly after pupation transferred to a 

 refrigerator for some weeks, aiid then alloived to develop in a noriiial 

 temperature-- — for, as has been shown, these pup^ from +°ova and 

 larvae resist the constant influence of the lowest tewperaturesin the English 

 summer — still emerging as var. teloides (here an " oval and larval " 

 form, following out also the facial tendency of the parent male in both 

 sexes) after nearly a month of pupal development. 



Broods I and II had, however, been treated to the two possible 

 extremes of temperature conditions connected with very hot, or with 

 very cool seasons, providing also for a very sunny exposed situation of 

 the ova and larvae, or for a well shaded position of the brood in a 

 wood. Under such conditions the ova and larvae would naturally 

 be influenced much more strongly in one direction or the other, 

 than under normal conditions. 



In conclusion, the following records of brood V show that when 

 the ova and larvse are reared m nearly normal conditions, then 

 then tliey do not any )iiore influence the pupal development in the degree, 

 as did the larvae of broods I and II, that then, in fact, the mean shade 

 and night temperature, acting on the pupae only, will cause \b,y. mesoides to 

 develop exclusively, and in the ej-treme form, not far from ab. fischeri, 

 while warmth and sunshine will produce var. teloides with equal 

 certainty and in great perfection. Both var. mesoides as also var. 

 teloides would be " pupal " forms in this case. 



Brood V. — Both male and female parent forms unknown. The ova developed 

 in their natural environment in the temperature of the season. The figures given 

 below for the oval stage are assumed, but I think are correct.* The young larvas 

 — captured soon after they had emerged — were all bred in conditions, which 1 will 

 call "normal warm," the temperature rising when the sun shone in the daytime 

 and not falling below 15°C. at night. (In the open air, the thermometer repeatedly 

 showed 5-8°C., the temperature only once keeping just above 15°C. in the night of 



* The "sensitive" stage is retained for weeks at a temperature of -f l°to +2°C. 

 development being suspended. If, for instance, larvae hanging up for pnpation are 

 placed in these low temperatures, they will hang unaltered for four weeks at least 

 — and, if brought into normal conditions, yet pupate and emerge as normal 

 specimens. High temperatures would, therefore, wipe out the effects of the long 

 " icing," and for that reason pupae should be left some days in 10-12°C. after 

 leaving the refrigerator. 



* The only fine days suitable for ovipositing, "within reach," were May 

 24th, 26th, 28th, and June 3rd. Comparison with my records make the first 

 and last dates impossible. The maxima and minima of the temperatures from May 

 2Gth to .June 10th, read as follows in °F. :— 71, 65, 74, 68, 63, -59, 67, 69, 72, 65, 61, 

 67, 78, 76, 76, 64° C. = daily shade maxima; and 43, 49, 49, 52, 45, 48, 45, 47, 

 45, 43, 47, 48, 53, 55, 52, 54 = nightly minima, beginning May 25th-26th. Mean 

 temperatures = 68.3°F.=20°C., by day; 48.8°F. =9.3""C., by night; and 58.4°F. 

 = 14. 70., for the whole period. 



