ACTION OF AMMONIA UPON SOME LEPLDOPTEROUS PIGMENTS. 205 



As alkali turned the pigment yellow, acids I thought might 

 prevent this, or even produce another colour. Accordingly the 

 wings were treated with a great many acids, the chief being 

 sulphuric, nitric, sulphurous, hydrochloric, phosphoric, and 

 acetic. With all these, when used in excess of the alkali, the 

 pigment was restored to its natural white colour. I also found, 

 that whenever the liquid employed was exactly neutral to both 

 red and blue litmus, the pigment remained unchanged, whilst the 

 slightest addition of alkali produced the primrose-yellow, and 

 when acid predominated the normal colour prevailed. Thus, we 

 see, this pigment is a good test for alkalinity. 



To enumerate all the species experimented upon would 

 occupy too much space, so I will only give the most important. 

 As some Continental species are mentioned, I have followed 

 Staudinger's arrangement. Papilio machaon and other Papilios 

 were unchanged, and the same may be said of the genus Thais. 

 Parnassius apollo, P. delius, and P. mnemosyne turned a pale 

 yellow. With such semitransparent species a deeper coloration 

 could not be expected, from the small amount of pigment present. 



None of the species of Aporia, Pieris, or Anthocharis showed 

 any alteration with ammonia, but Leucophasia sinapis and its 

 vars. lathyri, &c, exhibited a delicate primrose colour. Not a 

 single species in Colias, Rhodocera, Thecla, or Polyommatus was 

 changed; but the behaviour of the species of Lyccena was 

 extremely curious and somewhat unexpected. L. argiades, 

 argiolus, alsus, acis, alcon, avion, and euphemus remained 

 unaltered. L. bcetica, agon, argus, optilete, orbitulus, eros, 

 alexis, eumedon, amanda, adonis, meleager, jolas, and especially 

 agestis, corydon, and damon were beautifully suffused with 

 primrose on the under side and cilia, wherever the white 

 pigment occurs. It is difficult to say why some of the species 

 in this genera are unaffected, whilst others exhibit the most 

 gorgeous colouring; but in the case of a?-giolus at least this 

 may be accounted for. The pale bluish white of the under 

 side is not the result of white pigment at all, but is due to 

 reflected light from the almost pigmentless scales, in which a 

 change could not be looked for. All the species which were 

 examined in Nemeobius, Charaxes, Apatnra, Limenitis, Vanessa, 

 Melitcea, and Argynnis exhibited no change. In the SatyridaB, 

 besides Melanargia, (Eneis cello is clearly suffused with primrose 



