14. Females of _Pieris Napi_, captured on 27th-28th April, 1872, laid eggs on _Sisymbrium Alliaria_. The larvæ bred from these pupated on May 28th to June 7th. The pupæ, shortly after transformation, were placed on ice, where they remained till Sept. 11th (three months). Transferred to the hothouse on October 3rd, they produced, up to October 20th, 60 butterflies, all with the sharply-defined characters of the winter form. The remaining pupæ hibernated in a room, and produced:-- On the 28th of April, 3 males, 6 females. ” 4th of May, 1 female. ” 12th ” 4 males. ” 15th ” 1 male, 1 female. ” 16th ” 1 male. ” 18th ” 1 male, 1 female. ” 19th ” 1 female. ” 20th ” 2 males, 1 female. ” 23rd ” 2 males. ” 26th ” 1 male. ” 29th ” 1 female. ” 3rd of June, 3 females. ” 6th ” 1 female. ” 9th ” 1 female. ” 21st ” 1 female. ” 2nd of July, 1 female. --------------------- Total 15 males, 19 females. 15. Several butterflies from Exp. 14, which emerged in May, 1873, were placed in a capacious breeding-house, where they copulated and laid eggs on rape. The caterpillars fed on the living plants in the breeding-house, and after pupation were divided into two portions:-- A. Several pupæ, kept at the ordinary summer temperature, gave butterflies on July 2nd, having the characters of the summer form. B. The remainder of the pupæ were placed on ice immediately after transformation, and remained over three months in the refrigerator (from July 1st till October 10th). Unfortunately most of them perished through the penetration of moisture into the box. Only 8 survived, 3 of which emerged on the 20th of October as the winter form; the others hibernated in an unheated room, and emerged at the beginning of June, 1874. All 5 were females, and all exhibited the characters of the winter form. Notwithstanding a pupal period of eleven months, they did not possess these characters to a greater extent than usual, and did not, therefore, approximate to the parent-form _Bryoniæ_.