50 THE entomologist's record. 



varieties in this way would generally be variations in size, as in 

 the case of the before-mentioned species, Hypsipetes elutata, 

 and not variations in colour. 



My friend, Dr. Chapman, I know, always connects the 

 beautiful var. rosea of Cuspidia tridens with cherry {Ent. Rec. 

 ii., p. 31), but I do not know that he has formed any idea as 

 to the way in which the colour may be produced by this food, and 

 I simply mention the fact to show that other lepidopterists 

 consider that food does influence colour. Exact experiment 

 on the matter is undoubtedly needed. 



There is one way, however, in which food may more or less 

 indirectly produce a dark coloration. A plentiful supply of succu- 

 lent and nutritious food will generally produce insects of large 

 size, whilst an insufficient supply of food, or even a plentiful 

 supply of innutritious food will act in the opposite direction. 

 In these specimens, however, the smaller size is often accom- 

 panied by the markings being pressed much more closely 

 together, thus giving the insect a darker appearance. This is 

 especially the case if the ground colour be pale and the markings 

 dark, for then the area of the pale ground colour becomes 

 lessened, and the darker markings are developed in a smaller 

 space. It becomes hard to dissociate this form of develop- 

 ment from an indirect tendency to disease, or rather to a 

 change of constitution as Dr. Chapman terms it ; but all 

 instances of this kind appear to be only very indirectly caused 

 by food, and will be found, generally, to be governed by the 

 environment of the particular species. 



In the Ent. Mo. Mag., vol. xiii., p. 132, we find Mr. Birchall 

 attempting to show us that " there are great constitutional 

 differences in animals and plants, which are correlated with 

 differences of colour," and he refers to chaps, xxi. and xxv. of 

 Darwin's Animals and Plants under Domestication, where he 

 states it is shown " that black and dark-coloured animals 

 escape many diseases, are less liable to the attacks of parasites, 

 and will stand changes of temperature, which prove fatal to the 

 lighter coloured varieties." Unless in the case of true 

 albinisms, I should challenge this statement. We must bear 

 in mind that true " albinisms," which must not be confounded 

 with " leucochroisms," are generally looked upon by scientific 

 men as being a certain form of disease, or rather due to certain 

 conditions of disease, and we can readily understand that, if 

 this be so, the white varieties would necessarily be constitu- 

 tionally weaker than their darker brethren. Mr. Birchall then 



