84 THE ENTOJIOLOlilST's RECORD. 



of ocelliformity by the third spot being drawn up as a streak, and 

 separated from the urtiroe chain of markings ; the greyish-brown 

 parts around them, though crossed by black along the veins, suggest 

 the light grey ring round the ocellus in V. io. Underside foreiving : 

 The browned median area and the space between the 1st and 2nd costal 

 blotches are further darkened by reddish -brown streaks and spots ; the 

 rest of the wing-surface brown-black ; three " ioform " black dashes 

 in the margin instead of lunules, and three of the ocelliform white 

 spots of the upperside, marked by yellowish spots, as in T'. io. 

 Underside hindmmi: Colour black-brown, with one broad darker band ; 

 no 8- mark near the base ; the marginal markings partially disintegrate. 

 Opaqueness of the wiuffs : If held against the light the wings appear as 

 dark and untransparent as those of T'. io, and, also as in V. io, the 

 ocelliform spots of the upperwings show as faint points of light. 

 Antennae : Browned. 



To explain this mixture of markings in a specimen bred from n 

 normal ('. iirtieae larva, I would suggest that a (relatively) fixed species. 

 8uch as T'. iirticae, is the result of an established balance in a trinity 

 composed of two inner principles, the one neoform or progressive 

 (plasm-thought), the other palaeform or conservative (plasm-memory), 

 and one external — the influence of climate. Now plasm-memory, 

 primarily progressive in effect, but conservative in tendency, becomes 

 fixed by repetition of detail under the continuous influence of regular 

 climatic conditions." Thus the more constant (fixed) in facies 

 a. species appears, the more perfect is the balance l)etween 

 progressive vitality on one side and fixed plasm-memory, 

 built and upheld by regular climatic conditions on the other. 

 Obviously, to effect any change in the facies of a " flxed " species, 

 it is necessary to overthrow the established balance described. For 

 this purpose the chief factor of the external principle, normal tem- 

 perature, offers itself as easy to alter, and altered, iihnoDiial 

 temperature must, from the above, be capable of impairing (partially 

 suppressing) flxed (palaeform) plasm-memory, in which case both 

 the conservative factors opposed to progressive vitality would 

 be upset and the barrier to change removed. In the pupal 

 Ma(je " arrested or retarded development " (Standfuss) seems to 

 be the symptom of tbis suppression of "flxed" hereditism, as 

 is pointed out by the fact that the imagines from pupje of V. urticae, 

 which I bred in + 20 to + 48" (50°) C, emerged as normal (somewhat 

 thinly scaled) specimens in 4 days 15 hours, while the aberrations, 

 which resulted from the same tieatment began to appear after 7i days 

 (pi. vii., flgs. i, 8) and after 10 days (pi. vii., flgs. 1-3, 5-7). The nisola- 

 tion of the pupse of pi. vii., flgs. 1, 2 and 8 produced no separate 

 symptoms of this kind. 



In the inia;io staije the broad floods of colour, which give to certain 

 extreme forms the appearance of being painted in the young 

 secessionistic style of human art (pi. vii., flgs. 1, 5-7, 10, 11), may 

 perhaps be explained by a sudden burst of action on the part of vitality 

 according to the degree in Avhich conservative plasm-memory was 



* The annual cycle (changes) of the seasons, being regular, is fixing in influ- 

 ence. The two seasonal extremes sometimes even produce two correspondingly 

 different sets of fixed plasm-memory. Witness, for example, the brown, spotted 

 V. {Araschvia) levana and its black, white-banded summer form, vrorsa. 



