268 



KNOWLEDGE. 



[November 1, 1897. 



tion, while almost forswearing it in externals, and show 

 how there exists a subtle bnt rigid distinction between 

 eggs apparently exactly alike. Of the first, I will cite the 

 instance of the reed and marsh warblers, which, in 

 plumage and form, are so exactly alike as to puzzle all 

 but the most gifted taxouomers : the same is the case, 

 though to a less extent, with the willow and wood wrens, 

 and chiflchaff. But the eggs and nests of all these differ 

 unmistakably and strongly. Again, for many a year the 

 bearded reedling {Panunis biarmicus) was placed with the 

 titmice as a Pm-us, on grounds which appear very in- 

 sufficient. But, at last, the eloquent but silent appeal of 

 its nest, like a miniature coot's, and of its eggs, quite unlike 

 any other bird's with which I am acquainted, has procured 

 it not only a separate genus, but a separate family. 



To show how eggs apparently indistinguishable by the 

 eye may yet possess indisputable points of difference, I 

 may mention the smew's and wigeon's. The genuine eggs 

 of the former bird were, until very recently, extremely 

 rare. I had the good fortune to obtain a nest with the 

 characteristic grey down, ten eggs, and the skin of the 

 old bird, from Lapland direct, and could verify for myself 

 the diagnoses of authorities on this point. I found that in 

 every case the egg of il/. a/lielhi.t weighed over two and a 

 half scruples, which no wigeon's egg in my collection 

 reached by an eighth of a scruple. The thickness of shell 

 to which this extra weight is due, and which is charac- 

 teristic of all the eggs of the genus Menjus, attains its 

 maximum in those of the hooded merganser, which, with 

 the same cubic capacity as those of the wigeon, weigh 

 nearly half as much again. 



But not only by relative weight can the smew's eggs be 

 differentiated from those of other ducks : the texture is 

 unmistakable to a practised touch. After several essays, I 

 could pick out smews' from wigeons' in the dark, by passing 

 my nail along the surface, which in the former was smooth 

 and waxy, in the latter offering perceptibly more resistance. 



Colouring of Eggs. — This, as is well known, is due to 

 the ejection, from certain glands, of pigment upon the 

 egg as it issues from the oviduct. That it generally does 

 so broad end foremost may be inferred from the fact that 

 in most cases the pigment is concentrated at the larger 

 extremity, often in the form of a corona. Sometimes, as 

 with the sparrowhawk, the reverse is the case. I had a 

 clutch of seven in which the first egg (presumably) had a 

 splendid corona on the large end, which shifted gradually 

 down to the last egg, which had a little blotch on the 

 narrow end. Sometimes all the colour will be bestowed 

 upon the first egg of a clutch, leaving none for the others. 



The point, however, that would bear considerable 

 elucidation is the cause of redundance or entire absence of 

 pigment in the eggs of certain classes of birds. As a rule, 

 it will be found that the families of birds laying white 

 eggs are conspicuous for the brilliant colouring or metallic 

 lustre of their plumage, like the parrots, toucans, pigeons, 

 kingfishers, bee-eaters, humming birds, and woodpeckers. 

 It would seem as if so much pigment were expended 

 upon the feathers as to leave none for the eggs. But 

 against this theory comes the evidence of the owls, who 

 certainly are amongst the dowdiest of birds, yet lay 

 uniformly white eggs. It has been stated that those eggs 

 are white which, being laid in the dark, have no need of 

 protective colouring. But how would this theory account 

 for the fully exposed yet white eggs laid by the ducks, 

 goshawks, harriers, and many others '? Or, conversely, 

 such birds as Pliylli'sropus and Cisticola, which lay coloured 

 eggs in the dark, and the latter of which tints hers with 

 every conceivable variety of spot and colour '' It may be 

 that the birds' habits have been suddenly and forcibly 



changed, without any pressing inducement to change its 

 procedure. Possibly were the fan tail (Scha-nicola) to be 

 coerced to lay in the open, the lighter varieties of its egg 

 might be ultimately eliminated, and the most suitable 

 colour permanently adopted. It may be also, as with the 

 tree pipit, that some species are for ever " harking back " 

 to some ancestral idiosyncrasy. 



It cannot be questioned that the colouring of eggs is in 

 a large number of cases wonderfully protective. Those 

 who have looked for the eggs of plovers, oystercatchers, 

 or coursers, can testify to the great difficulty of detecting 

 them amid their surroundings. But he who, on the 

 strength of these instances, would set up to be an absolute 

 "protectionist," would find it difficult to account for such 

 a " free-trader " as the goatsucker, who will display her 

 marble eggs upon a background of fern or bark, admirably 

 calculated to show them up. Yet he may solace himself 

 with the reflection that this class of bird does not fly by 

 day, but sits perfectly close, and in plumage so absolutely 

 resembles her environments as to defy detection. 



A final question. Does any bird lay an egg resembling 

 that of a reptile sufficiently to warrant the presumption of 

 a closer approach on its part to the line of demarcation 

 between the two classes — the scientific frontier, so to 

 speak, on which stands, weird and solitary, the mystic 

 Archasopteryx ? If the thrush, in its form, song, nest, 

 and eggs, be regarded in all respects as the most perfect 

 type of a bird, then we might take the penguin as repre- 

 senting the other extreme, as it has fins for wings, scaly 

 feathers, spends the bulk of its time under water, cannot 

 fly and hardly walk, and lays its egg on the bare rock. 

 That is so ; but, unfortunately, it only lays one egg, and the 

 reptiles are conspicuous for their enormous productiveness. 

 On the other hand, the ostriches, like their giant fossil 

 ancestors, lay a number of eggs, and incubate them vicari- 

 ously in the sun-heated sand — a very reptilian habit. 



I will conclude, as I began, with a quotation from 

 Seebohm, one of our greatest oologists : "The new 

 impetus given to the study of all branches of natural 

 history by the discoveries of Darwin and Wallace, has at 

 length reached oology, and an additional interest is given 

 to it from the light which it throws in many cases upon 

 the relationship of species and genera." 



THE NEW STATE LABORATORY. 



VERY little, indeed, was known, among the general 

 public, of the chemical operations which have, for 

 half a century, been carried on in makeshift 

 rooms at Somerset House, until the new Labora- 

 tory was opened in Clement's Inn Passage on the 

 1st October ; and, if possible, less was known of the real 

 functions of such an institution. When the expense of a 

 luxurious public establishment for carrying on chemical 

 manipulations is placed before the groaning taxpayer, 

 one might ask, not unreasonably, what is the use to the 

 people at large of such an accessory in the State 

 machinery ? Moreover, evidence is not wanting that, in 

 spite of the great increase in the diffusion of knowledge in 

 recent years, there are not a few among even those who 

 wield considerable influence in municipal affairs who see 

 no use at all in public laboratories, except as a means of 

 increasing unduly the demands on the private householder's 

 pecuniary resources. A lamentable exemplification of this 

 short-sighted policy is even now too apparent in the 

 calamity which has overtaken the inhabitants of Maidstone. 

 This town has enjoyed the reputation of being a healthy 

 locality with a low death-rate and an enviable freedom 

 from typhoid fever — circumstances which, when the first 



