176 Dr. H. Eltringham on Danaine Butterflies. 



secretion of the wing is easily evaporated and must be 

 protected, yet in A. egialea the scales cover the glands so 

 imperfectly as to be probably useless for such a purpose. 



It is to be feared that the study of the chemistry of these 

 secretions is only possible in those countries where the 

 insects may be obtained in large numbers and in fresh 

 condition. Meanwhile I would proffer one or two sug- 

 gestions to those collectors abroad who may take an 

 interest in the subject. In detecting delicate odours and 

 locating their origin it would seem that some success might 

 be attained by using a glass tube one end of which would 

 fit the human nostril the other being drawn out to a com- 

 paratively narrow diameter. The narrower end being 

 applied to suspected centres of emission the odour might 

 reach the human olfactory epithelium in a less diluted 

 form than it necessarily does under ordinary circumstances. 

 Furthermore, a number of crushed wing-brands might be 

 placed in a small phial and warmed so that the scent might 

 become sufficiently concentrated to be perceptible. Again, 

 assuming a plentiful supply of material, might it not be 

 possible to apply the principles of perfume manufacture 

 to the extraction of any scent that may be present in certain 

 organs ? Large numbers of the scent-brands of some com- 

 mon species could be crushed and mascerated with a very 

 small quantity of clarified lard and the product distilled 

 with alcohol.* Or by means of a tube with a tightly 

 fitting screw, and a minute aperture at one end, an appreci- 

 able quantity of the scent material might be expressed from 

 a mass of the brands. 



Finally, whilst fully recognising the excellent contri- 

 butions already made to our knowledge of the subject by 

 the authors mentioned in the course of this paper, it would 

 seem that there still remain opportunities for compre- 

 hensive researches covering an interesting field, which it 

 is to be hoped will attract the attention of our many 

 capable workers in the tropics. 



* Dr. Dixey has already sho\vn that in the case of certain Pierines 

 there may be made from the wings an alcolioUc extract possessing 

 the cliaracteristic odour of the species from which it was prepared. 

 See Proc. Ent. See. Lond., p. Hx, 1905. 



Explanation of Plates XI-XX. 



{See Explanations facing the Plates.] 



June 26, 1915 



