ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
469 
structures intermediate between these, always have a wall, and that there 
is free nerve-ending on the surface of the body. When these organs have 
a thick chitinous wall they can only serve for the perception of mechani- 
cal stimuli ; when they are thin-walled they are adapted for mechanical, 
thermal, and chemical stimuli. The thin-walled hair-like structures are 
most important as olfactory and gustatory organs. The sense of 
equilibrium, and in many cases that of hearing, has no specific sensory 
organ among Insects, but many and various dermal sensory organs 
combine to effect their purpose. The value of the several senses to the 
animal varies among Insects, and there is a corresponding variation in 
the development of the several sense-organs. 
Variation in Colour of Cocoons.* — Mr. W. Bateson has tested the 
view of Poulton that the variation in the colour of the cocoons of 
Eriogaster lanestris and Saturnia Caspini , which are sometimes dark brown 
and sometimes much lighter, is due to the colour of the substances to 
which they are attached. He finds that light-coloured cocoons are pro- 
duced when the larvae are confined in either vhite or dark substances, 
but that when left with their food the cocoons are dark. As many of 
the larvae evacuate a brown substance, and as there is good evidence that 
a brown meconial fluid is voided by caterpillars which are removed 
and shut up before they spin, it is suggested that the cocoons of the 
secluded larvae are white by reason of the previous voiding of the brown 
fluid and the consequent absence of a supply of colouring matter. 
Effects of Artificial Temperature on Coloration of Species of 
Lepidoptera.f — Mr. F. Merrifield has confirmed, with Selenia illunaria 
and S. lunar ia, the results attained to with S. illustraria and Ennomos 
autumnaria ; the imagines are materially influenced in their colouring by 
the exposure of the pupa in its penultimate stage to a moderate difference 
of temperature ; the limits being 57° F. and 80° F., it is found that 
the lower causes the greater darkness of colour. Markings are very 
materially affected by exposure to a temperature of about 83° F, 
Scale-like and Flattened Hairs in Lepidopterous Larv8e4— Prof. 
A. S. Packard calls attention to the scale-like hairs found in the larvse of 
Gastropacha quercifolia and G. americana , in Clistocampa proxima and 
various Noctuina. They appear to be of use in making the dorsal tufts 
more conspicuous, and they are interesting as examples of the accelera- 
tion of development of the setae in the larval stage. 
Venation of the Wings in Lepidoptera.§ — Dr. A. Spuler describes 
what he believes to be the fundamental type of venation. It represents 
a stage through which all Lepidoptera have passed, and it is congruent 
with what occurs in Neuroptera, Panorpata, Trichoptera, and Diptera. 
In Neuroptera, Trichoptera, Panorpata, and two families of Lepidoptera, 
the plan is the same for anterior and posterior wings, in most Lepido- 
ptera a reduction of the venation has occurred in the hind pair. Owing 
to the difficulties of description and nomenclature without illustrative 
figures we cannot do more than notice Spuler’s general result. He 
compares the venation of Lepidoptera with that in related orders, takes 
due account of ontogenetic corroborations, and considers several families 
of Lepidoptera in detail. 
* Trans. Entomol. Soc. London, 1892, pp. 45-52. t Tom. cit., pp. 33-44. 
% Ann. and Mag. Nat. Hist., ix. (1892) pp. 372-5 (1 fig.). 
§ Zeitschr. f. Wiss. Zool., liii. (1892) pp. 597-646 (2 pis.). 
