July 1, "1SG8.J 



HARDWICKE'S SCIENCE-GOSSIP. 



151 



and features that, simple as they may seem, may 

 hereafter be of importance when interpreted to 



Fig. 1-13. End of poison bag of Wasp, as a polariscopic 

 object, x 40. 



the establishment of the laws of which they are 

 examples. 



Armagh. Lewis G. Mills, LL.B. 



MONSTROSITIES IN EGGS. 



npHE double egg described by Mr. A. Hawkins 

 -"- is of occasional occurrence. I have even 

 heard of a treble egg, each being perfect with its yolk 

 and germ. I have seen the germ extracted from an 

 internal egg, so that it is possible that it might be 

 hatched, although I have not heard of an instance. 

 Air is believed to be necessary for the development 

 of the germ (hence the porosity of the shell in 

 most eggs), but the wrapping of albumen might 

 not entirely exclude air from the internal egg, and 

 moreover an air bubble (follicle) is usually found 

 in these monstrous eggs. Very little if any air 

 must be necessary to the development of some 

 chicks ; how, otherwise, would the chicks of the 

 emeu, mooruk, and ostrich be formed ? The eggs 

 of the latter, especially, have sometimes no visible 

 pores, being 'smooth and dense like ivory. That 

 these eggs must be practically so is obvious from 

 their keeping fresh for two years, without any var- 

 nish or grease ; and it is probable that they are 

 susceptible of being hatched for some months after 

 being laid. There is a great difference, however, 

 in the appearance of the eggs laid in Northern and 

 Southern Africa ; hence some naturalists have 

 inferred a distinction of species in the parent birds ; 

 but this has, I think, yet to be established. The 

 eggs from North Africa are smooth, and without 

 punctures ; those from South Africa are deeply 

 punctured. I have one from Central Africa where 



the punctures are much less marked. The North 

 African eggs are larger than those in the South, 

 but considering the number of eggs that are ob- 

 tained, there is wonderfully little difference in size. 

 Some time ago, at the British Museum, Mr. George 

 Gray, F.R.S., showed me one of half the normal 

 size ; neither of us had seen another. Abnormalities 

 in the eggs of the emeu are perhaps rather more 

 common, but still very rare. I have lately obtained 

 two, taken in the heart of Australia, of the B. 

 eroratics, the spotted emeu. These had been two 

 years unblown ; one was half the natural size, the 

 other was pinched in in the centre, being a sort of 

 twin egg, and one-third less in bulk than usual. 

 We have much to learn yet on the causes of these 

 abnormalities. I have been at pains to collect all 

 the monstrosities in eggs I can get for the last 

 fifteen years. It is wonderful what extremes of 

 size we find in those of the common hen. I have 

 one little above the size of the wren, and another 

 four ounces and a quarter in weight. Some are very 

 fantastic in shape, being like a thistle-head or 

 pippet funnel in form, either straight or curved - t 

 others remind us of a cow's horn ; and a few are 

 crumpled into deep furrows. Some of the smallest 

 eggs have been laid, to my certain knowledge, by 

 an old hen, which, having given over the normal 

 duties of laying and incubation, thought proper to 

 assume a bastard male attire, and was soon dubbed 

 a cock : this was in autumn. In the following 

 spring she laid three eggs, rough shelled and yellow, 

 very round, and not exceeding an inch in length. 

 She was a " cockatrice " indeed, but her eggs being 

 blown, were found to contain neither yolk nor 

 germ. 



I have several nests of eggs containing abnormal 

 examples intermixed with normal ones; thus a 

 greenfinch's nest contains one egg of a quarter the 

 natural size, with the concentrated spotting of a 

 full-sized egg. A second nest has one egg entirely 

 without spots. These aberrations are commonly 

 attributed to fright, weakness, or maternal anxiety^ 

 but we want something more definite. The theory 

 so strongly dwelt on by M. Baldamus affords a 

 solution for many difficulties connected with the 

 form and colouring of birds' eggs. It is as old as 

 the days of Jacob and Laban, but was then applied 

 to another class of animals. It supposes an impres- 

 sion' made on the sensorium of the female cuckoo 

 by the sight of the eggs in the foster-parents' nest, 

 which influences the colouring of hers, and induces 

 an approximation in hue between them. When a 

 cuckoo lays in a hedge-sparrow's nest, whose eggs 

 are blue-green, her egg is greenish, as also in that 

 of the reed or sedge warbler, and in that of a tree 

 pippit, whose eggs are olive or reddish, those of 

 the cuckoo approximate towards this colour; and in 

 those of the pied wagtail, whose eggs are white, 

 spotted with ash, a similar approach to the ash 



