i40 • iMfe entomologist's KEcokb. 



Mr. Hellins, in the article from which we have already quoted, 

 makes the following remarks anent colour changes : — " A third question 

 witli regard to eggs is this — Do eggs of the same species vary in colour ? 

 or do they always go through tlie same changes of colour in approaching 

 maturity ? Mr. Buckler and myself have noted a most decided variation 

 in the eggs of Ornyia antiqua ; often they are of a dirty whitish hue, 

 with central brown spot, but sometimes we have met with batches which 

 were ([uite reddish-brown all over ; I believe, too, the eggs of Dicrannra 

 vinula vary considerably in the depth of their brown colouring. I have 

 notes of a few eggs of Hepialm sylchms, which I once secured ; when 

 laid they were all of a dull white, and most of them remained so, with 

 the exception of a tinge of yellow, wliich came over one side ; but one 

 egg became deep j^ellow all over, and the larva from it when hatched, 

 was of a much deeper yellow than the rest, but I did not manage to rear 

 it so as to see wliether this difference remained throughout its growth. 

 I have also notes of various batches of eggs of Cheimatohia brumafa, 

 which did not all seem to go through the same changes of colour, some 

 of them not showing the dark hue which others j^ut on at the last." 



That most of the clianges in colour are very closely connected with tlie 

 developmental clianges taking place within, will be manifest, if the egg 

 be kept inider microscopic observation. The first change, which occurs 

 very soon after the egg is laid, probably represents the transition of the 

 contents of the egg from their primal homogeneous condition, to the 

 condition which obtains at that period when the blastoderm layer is 

 developed. There is sometimes a distinct change of tint, at others, the 

 whole surface becomes completely covered with black dots ; this change 

 would appear to correspond with the separation of the contents from 

 the cell- wall. 



The second change appears to accompany the formation of the germ- 

 inal band, and appears to be intensified as the growth of the embryo 

 continues. This probably accounts for the general darkness of the tint 

 assumed in this stage, dark brown, red, purple, lead, and other tints 

 being frequent, and lasting sometimes for a considerable space of time. 



The third change generally exhibits an intensification of the colour 

 in the jjrevious stage, except that the apex and frequently the base of 

 some eggs become pale again. This is an external sign that the embryo 

 is a2)in-oaching maturity. 



These three changes in colour, therefore, are the naked eye appear- 

 ances of the egg during the condition of eml)ryonic development, and 

 may be said to separate the four periods into which embryonic life may 

 be divided. 



Dr. Chapman, in his papers " On the genus Acronj'cta and its 

 allies," mentions the following facts. The egg of Viviinia auricoma, 

 which is pale creamy when first laid, passes into a rich reddish chocolate- 

 brown, with numerous white or creamy spots. That of V. myricae, is 

 at first yellow, but soon becomes of a pale salmon-pink, and finally, of a 

 purplish-brown, with paler reddish-brown spots. In V. menyanfhid/K, 

 the egg, at first yellowish, soon becomes red, and at full colour is 2)erliaps 

 brown rather than red, getting nearly black as the young larva 

 apjuoaches hatching. That of V. rcnosa, from sulphur yellow, becomes 

 reddish-) irown, with paler markings. In V. rumicis, tlie egg, Avhen first 

 laid, is white, or faintly greenish in tint, and soon becomes yellowisli, 

 •with a net-work of red streaks ; there is a central red or brown dot on 



