380 THK ZOOLOGIST. 
known and undesirable garden moth, Abraxas grossulariata, in 
which the larva and pupa are both prominently marked with 
yellow and black, and the perfect insect exhibits the same 
prominent hues. Plants often develop colour in response to 
purely environmental conditions. Mr. Scott Elliot observes :— 
‘“‘T have noticed everywhere that in places .... where there is 
plenty of sunlight and not enough humidity to form a large 
amount of branches and leafage, the surplus nourishment is 
usually disposed of in bright colouring. A curious instance of 
this effect carried to extremes is an orchid (Disa erubescens, 
Rendle), which is all over the curious red colour which one often 
sees on the leaves and stems, e.g. of our common Herb Robert 
in England. Other instances of this sort of flora may be seen, 
e.g. on the limestone hillocks about Alexandria and on Table 
Mountain summit.”* Mr. Wallace enumerates as instances of 
colour needing ‘‘no special explanation,” those alge and fungi 
which have bright colours—the ‘‘red-snow’”’ of the Arctic regions, 
the red, green, or purple seaweeds, the brilliant -scarlet, yellow, 
white, or black agarics, and other fungi; also the varied tints of 
the bark of trunks, branches, and twigs, which are often of 
various shades of brown and green, or even vivid reds or yellows.t 
Prof. Marshall Ward also remarks:—‘‘ The red colour often 
assumed by parts of plants other than flowers, especially young 
leaves, afforded an instance of the danger of pushing an explana- 
tion too far. In many instances it doubtless served to absorb 
some of the sunlight, and so protect the chlorophyll of young 
organs; but such a case as the red colour in the lower layers of the 
floating leaf of a water lily demanded some other explanation.” f 
Dr. Bonavia, amid much speculation, has truly written: ‘ Phzno- 
gams, such as the carrot and beetroot, develop their orange and 
crimson colours in what we should consider as total darkness.” § 
We must all agree with Darwin that ‘‘hardly any colour is finer 
correspond with that of the mollusc. The latter may be of an intense black, 
the shell being quite white ; the ‘animal’ may be a most brilliant creature 
with a variety of many colours, and its test merely of some uniform sombre 
hue.” (Edgar Smith, ‘ Roy. Nat. Hist.,’ vol. vi. pp. 822-3.) 
* ¢A Naturalist in Mid-Africa,’ pp. 93-4. + ‘Darwinism,’ p. 302. 
{ ‘Royal Institution Lecture,’ February 18th, 1896. 
§ ‘Phil. Notes on Botanical Subjects,’ p. 89. 
