[58] The experiments upon _Papilio Ajax_ and _Phyciodes Tharos_, described in this Appendix, were made by Mr. W. H. Edwards (see his “Butterflies of North America;” also the “Canadian Entomologist,” vol. vii. p. 228-240, and vol. ix. p. 1-10, 51-5, and 203-6); and I have added them, together with some hitherto unpublished results, to Dr. Weismann’s Essay, in order to complete the history of the subject of seasonal dimorphism up to the present time.--R.M. [59] This is a striking illustration of the diversity of individual constitution so frequently insisted on by Dr. Weismann in the foregoing portion of this work. [60] The reader who wishes to acquire a detailed knowledge of the different varieties of this butterfly, of which a very large number are known, must consult the plates and descriptions in Edwards’ “Butterflies of North America,” vol. ii. [61] Mr. Edwards has shown also that _Argynnis Myrina_ can lay fertile eggs when but a few hours out of the chrysalis. Canad. Ent., September, 1876, vol. viii. No. 9. [62] Mr. Edwards remarks that the habit of becoming lethargic is of great service to a digoneutic species in a mountain region where it is exposed to sharp changes of temperature. “If the fate of the species depended on the last larval brood of the year, and especially if the larvæ must reach a certain stage of growth before they were fitted to enter upon their hibernation, it might well happen that now and then an early frost or a tempestuous season would destroy all the larvæ of the district.” [63] Compare this with Weismann’s remarks, pp. 19-22, and 53. [64] See Canad. Ent., vol. ix. p. 69. [65] Figures of the different forms of this species are given in vol. i. of Edward’s “Butterflies of North America.” [66] Only the species of _Smerinthus_ can be made to lay eggs regularly in confinement; _Macroglossa Stellatarum_ laid a number in a large gauze-covered breeding-cage; the species of _Deilephila_ could not be induced to lay more than single ones in such a cage. From species of _Chærocampa_ also I never obtained but a few eggs, and from _Sphinx_ and _Acherontia_ never more than single ones.