HARDWICKE'S SCIENCE-GOSSIP. 



5i 



points raised by Mr. Croll, but I wish to draw 

 attention to the fact that, according to this theory, 

 meteorites may be broken fragments of two dark 

 stellar masses which were shattered to pieces by 

 collision, fragments projected outwards too quickly 

 to be converted into the gaseous condition, and 

 passing outwards into space with a velocity which 

 would carry them beyond the risk of falling back 

 into the nebula. They would then continue their 

 progress in separate forms as meteorites. If this 

 be their origin, then meteorites are the offspring 

 of sidereal masses, and not their parents, as Mr. 

 Lockyer concludes. In the same way Mr. Croll 

 accounts for the origin of comets, supposing that the 

 materials composing them were probably projected 

 from nebulas by the expulsive force of the heat of 

 concussion which produced the nebulae. Some of 

 them, especially those with elliptic orbits, he says, 

 may have possibly been projected from the solar 

 nebula. This, it will be remembered, agrees with 

 our previous account of the origin of comets. Mr. 

 Proctor thought that comets of the solar system were 

 formed, the larger ones by eruption from the sun and 

 the smaller ones by eruption from the major planets. 

 After pointing out in his work, " Other Worlds 

 Than Ours," by a calculation which I cannot now 

 follow, the enormous number of meteorites in our 

 system and also the well-known connection between 

 meteorites and comets, he rejects the nebular 

 hypothesis, and advances, instead, the meteoric 

 hypothesis. He supposes that originally the solar 

 system consisted of a mass of meteorites in motion 

 and that these aggregated around various centres to 

 form planets ; and he considered the strongest evidence 

 in favour of his hypothesis was the fact that the sun 

 and planets are growing, however slowly, by the 

 meteoric hail which falls continually upon them. 

 Without going further into this hypothesis, which 

 appears in " Other Worlds Than Ours," it does not 

 appear satisfactorily to account for the formation of a 

 sun or of such planets as Saturn and Jupiter : it does 

 not account for the graduated density of the planets 

 which we have noted as existing, it does not allow 

 for the formation of nebulse such as we know actually 

 exist in space ; and the motion of planets formed, as 

 he suggested, out of meteor swarms, would not, I 

 consider, produce such a series of planets in one 

 plane and with so great a uniformity of rotation 

 and revolution as we have in the solar system. 

 If this article were not already so long, I should 

 have been glad to have devoted more time to 

 Mr. Proctor's theory, but my subject was the 

 nebular hypothesis, and that I have endeavoured 

 to state fully and fairly. In doing so, all the 

 points which Mr. Proctor raises by way of objection 

 have been considered, with the exception of the 

 difficult question of planetary periods, as to which he 

 does not suggest that his theory offers a more 

 reasonable explanation than the nebular theory. 



The nebular hypothesis is so highly probable as to 

 have gained almost universal acceptance. In fact, it 

 contains very little of a hypothetical nature. Mr. 

 Mill says : " It is an example of legitimate reasoning 

 from a present effect to its past cause, according to 

 the known laws of that cause." And I would add, 

 if it is not a true theory, one would almost think it 

 deserves to be so. 



*»* The writer is specially indebted to John Fiskc for the 

 materials used in the above article. " The History of a Star," 

 by J. Norman Lockyer, published in the "Nineteenth 

 Century " of November last, after the above article was written, 

 requires consideration. 



THE COLOURING OF THE EGGS OF 

 WILD BIRDS AT THE SMALLER END. 



A FEW further remarks on this subject may not 

 be out of place now the season for making 

 observations is coming on. 



In looking over a number of smaller-end-marked 

 eggs, it will be seen that those of the Falconida.* 

 retain their normal form and character, whilst those 

 of several other birds assume two distinct types. In 

 one type the eggs are short and abruptly pointed, in 

 the other they are long and narrow. Mr. T. C. 

 Wright mentions this type in the January number of 

 this journal. The former 'type sometimes forms the 

 greater portion of a full clutch, but as a rule the eggs 

 of the latter type are found as single specimens. I 

 have now before me two clutches of the first-men- 

 tioned type, each containing five eggs, one being of 

 the robin {Erithacus riibicula), in which three of the 

 eggs are marked at the smaller end, the other of the 

 white-throat {Sylvia cinered), in which two are 

 marked at the smaller end, the remaining eggs in 

 both clutches being faintly marked in the usual 

 manner. 



Two misshapen eggs in a clutch of whinchat 

 {Pratincola rubetra) have a well-defined zone of 

 colour around the smaller end. An egg of the pied 

 wagtail, and also one of the great tit, show what may 

 be termed the false marking, but as the last two 

 mentioned eggs were taken by pilfering collectors, I 

 have no history with them. The birds referred to 

 above all lay full-sized eggs, and not more than two 

 per cent, are coloured at the smaller end. 



The red-legged partridge, which lays a small egg, 

 has a strong tendency to draw the colour to the lower 

 portion of its eggs. 



It was suggested that the large percentage of the 

 eggs of the Falconidaa having the false marking was 

 owing to the egg becoming reversed in the oviduct 

 during the abrupt turns, twists, and gyrations per- 

 formed by the bird in the capture of its prey. I doubt 

 if there is much cogency in this suggestion, for a 

 series of clutches of the swallow (Hirundo rustica) 

 do not show a trace of false marking, and this bird 

 performs during a day's flight far greater aerial 

 gymnastic feats than the Falconidse. 



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