30 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
He also thinks that a hypothesis of this kind sheds much light upon 
such phenomena as seasonal and sexual dimorphism, natural and artificial 
colour variation, the development of local races, and the similar colour 
phenomena of Lepidoptera, which are all to be explained as showing 
that butterflies are, from internal causes, constantly varying in colour in 
a definite direction, and that special stages in evolution may be empha- 
sised by particular, usually external, influences. 
Coloration of Insects.* — Herr T. Garbowski briefly criticises Brunner 
von Wattenwyl’s volume on this subject. From the philosophical point 
of view he maintains that the result of Brunner’s reasoning is to suggest 
that the coloration of insects has no relation to the needs or structure 
of the organism, but is merely an expression of the Supreme Will. By a 
series of concrete examples, Garbowski further endeavours to show that 
Brunner’s results are inconsistent with the facts as known to entomo- 
logists. 
Development of Markings of Blitterflies.f — Grafin Maria von 
Linden has studied the wings in the pupae of various butterflies, 
especially species of Vanessa and Pajpilio, in order to determine the 
question whether, in the ontogeny of the colour and markings, the 
characteristics of the adult develop slowly from primitive markings, 
or appear suddenly. The results show that, especially in the case of 
the less specialised species, there is in ontogeny a gradual development 
of the markings ; and from this development hints as to the phylogenetic 
origin of the markings may be gathered. The author is of opinion that 
the course of development entirely supports Eimer’s well known views 
in regard both to the origin of markings and patterns, and of species 
themselves. As to the development of colour, the first tint to appear 
is yellow, and there is then a gradual progression through orange, red, 
brown, to black. Optical colours, such as blue, appear later than the 
dark tints, and are confined to scales containing dark pigment. 
Coloration of Lepidoptera.t — Dr. M. Baer has investigated the 
structure of the wing-scales, in the diurnal butterflies in its relation to 
the colours, and publishes a concise summary of his results. These are 
in the main similar to those of preceding observers, but are in some 
respects more detailed. He divides the colours into (1) those due only 
to pigment, (2) optical colours, (3) colours produced by the combination 
of pigment and structure. (1) Except in the Pieridae, he finds that the 
pigments are uniformly diffused and not granular; and, like previous 
observers, he has found pigments of all tints except blue, violet, and 
intense black. Green and white pigments he finds to be rare, the former 
apparently occurring only in the wing membrane. In the Pieridae the 
scales are few in number, often quite devoid of sculpture, and deeply 
pigmented with granular pigment. (2) The author’s observations on 
optical colours entirely confirm those of Spuler. (3) Colours such as 
reddish-violet, greenish -blue, emerald-green, are produced by the super- 
position of scales containing bright pigment and scales exhibiting 
optical colours. 
* Biol. Centralbl., xviii. (1898) pp. 456-8. 
t Zeitschr. f. wise. Zool., lxv. (1898) pp. 1-49. f Tom. cit., pp. 50-64. 
