12. Larvæ of the fourth generation, found on September 22nd, 1872, were divided into two portions:—
A. Placed for pupation in an orchid-house at 12°-25° R., and allowed to remain there till December. In spite of the high temperature not a single butterfly emerged during this time, whilst pupæ of Vanessa C-album and Pyrameis Atalanta, found at the same time, and placed in the same hothouse, emerged in the middle of October. From the middle of December the pupæ were kept in an unheated room, and they emerged very late in the spring of 1873, all as Levana:—
| On the | 6th | of June, | 7 | Levana. |
| ” | 8th | ” | 2 | ” |
| ” | 11th | ” | 2 | ” |
| ” | 12th | ” | 1 | ” |
| ” | 15th | ” | 6 | ” |
| ” | 16th | ” | 1 | ” |
| ” | 19th | ” | 2 | ” |
| Total | 21 | ” | ||
B. Kept in an unheated room during the winter. The butterflies emerged from the 28th of May, all as Levana.
Experiments with Pierinæ.
13. Females of Pieris Rapæ, captured in April, laid eggs on Sisymbrium Alliaria. From these caterpillars were obtained, which pupated on 1st-3rd June. The pupæ were placed on ice from June 3rd till September 11th (0°-1° R.), and from September 11th till October 3rd in the hothouse (12°-24° R.), where there emerged:—
| On the | 23rd | of October, | 1 female. |
| ” | 24th | ” | 1 female. |
| ” | 25th | ” | 2 males, 1 female. |
| ” | 26th | ” | 1 female. |
| ” | 28th | ” | 1 male, 1 female. |
| Total | 3 males, 5 females. | ||
All these were sharply impressed with the characters of the winter form, the females all strongly yellow on the upper side, the males pure white; on the under side a strong black dusting on the hind wings, particularly on the discoidal cell. One pupa did not emerge in the hothouse, but hibernated, and gave in a heated room on January 20th, 1873, a female, also of the winter form.
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. | ||