September 2, 1895.] 



KNOWLEDGE 



205 



his wonder that more have not been protected. He 

 evidently does not consider their protection unnecessary. 



Mr. Johnson still speaks of " natural selection " 

 as "an active agent which adapts," and as "alto- 

 gether an environmental 

 force." Now I must again 

 deny, as has been repeat- 

 edly done by much more 

 competent authorities, that 

 any such characters can be 

 ascribed to it. There can be 

 no agency, no force in mere 

 selection. He, and other evo- 

 lutionists are only deluding 

 themselves by their improper 

 conception, and use of a 

 term which cannot, in any 

 circumstances, imply what 

 they attribute to it. 



Mr. .Johnson says that 

 " all modern writers have 

 employed the term ' mimicry ' iu a metaphorical sense." 

 I am not aware that any scientific men employ metaphor 

 when enunciating truth. Certainly neither Darwin nor 

 Wallace so uses it. 



Dr. Marshall now explains that by mimicry is meant 

 "an accidental resemblance which is increased by heredi- 

 tary transmission " ; but how can hereditary transmission 

 incrmse resemblance, the resemblance not proceeding from 

 any cause which might accompany the transmission ? And 

 will accidental resemblances be transmissible at all ? My 

 experience is that they are not continued in future 

 generations. 



Dr. Marshall answers my query " ^^'hat has all this to 

 do with origin of species 1 " by referring me simpliritcr to 

 Mr. Darwin's book on the subject. Now it so happens 

 that I have lately had occasion to study carefully both 

 Darwin's and Wallaca's books on the colouring of animals, 

 and I have not found a single sentence in either which 

 seeks to connect the interesting natural facts which they 

 relate with the subject of their discussion, viz.. Origin of 

 Species. Dr. Marshall must be more explicit. 



I have still another difficulty to place before him for 

 solution. In his article in your .June issue, he said that 

 the butterflies referred to were protected when perched, but 

 butterflies are not always perched. My observation of 

 them leads me to believe that they spend the greater part 

 of their brief butterfly existence in fluttering happily from 

 flower to flower in the sunny summer air. When thus 

 engaged, the white uader-wing can, of course, be no pro- 

 tection, but rather the reverse, while the brilliant upper- 

 wing must present a very conspicuous object to their 

 enemies the birds, and it is thus, as I have repeatedly 

 seen, that the poor butterfly is caught and killed. How 

 comes it, may I ask Dr. Marshall, that natural selection 

 has provided no protection for the butterflies when most 

 exposed to danger, while supplying it when they are com- 

 paratively safe ■? This is surely very inconsistent and 

 inconsiderate in his friend, and I think requires further 

 elucidation. Wm. Miller. 



Broughty Ferry, 1st August, 1895. 



*^ * 



OPTICAL PHEJfOMENON. 



Dear Sir, — I enclose a sketch of the optical phenomenon 

 observed at Juvisy on September 12tli, 1894, 5h. 45m., 

 Paris mean time, which may be described as follows : — 



The sun was nearly setting, when, all of a sudden, 

 two very narrow lines, liice telegraph wires, but nhite, 

 originating from a point of the western horizon near 



the sun, rose in gentle curve towards the east, 

 attaining on the south their maximum height (20^) above 



the horizon. 

 Tlie lines 



were probably parallel, but owing 



(apparently) to perspective, their distance, which was 

 over the south some 1' apart, was only half that amount 

 in the vicinity of the sim. 



The apparition lasted more than half an hour, having 

 gradually faded away at (ih. 22m. 



M. Flammarion, who happened to be present, observed 

 also this remarkable phenomenon. 



E. M. Antoniadi. 



SATELLITE EVOLUTION. 



By Miss A. M. Clerke, Authoress of " The System of the 



Stars " anil " A Popular History of Astronomy during the 



Nineteenth Century " <(■€., dc. 



THE decease of decrepit hypotheses is characteristic 

 of a time of progress, and those dealing with the 

 origin of things are apt to be particularly short- 

 lived. For Nature is, beyond estimation, manifold 

 in its workings. The unravelment of one alone 

 often overtaxes oar powers ; how much more the simul- 

 taneous interaction of many ! Thus our knowledge is 

 necessarily made up of partial truths, and partial truths 

 are on occasions indistinguishable from crass falsehoods. 

 Nor is it easy to be wise even after the event. We see 

 that certain things have come to pass, but the " how " 

 evades us. The embodied idea can be apprehended, while 

 the method of its realization remains obscure. 



It was with the light-hearted intrepidity commonly 

 associated with imperfect information that Laplace attacked 

 the problem of the growth of the solar system. He was 

 suspiciously successful. In a simple " Note,'' he described 

 a process adequate to the purpose, not merely in his own 

 judgment, but in that of the whole contemporary learned 

 world. His speculation remained unchallenged for half- 

 a-century. Subversive facts indeed accumulated ; yet 

 it was long before they were thought worth the trouble 

 of explaining away. When at last the task was attempted, 

 it was found to be impossible. The French geometrician's 

 neat and complete theory collapsed. That the sun, the 

 planets, and their satellites were somehow derived from a 

 primitive rotating nebula could scarcely indeed be contro- 

 verted, but the modii,': operandi continued obscure. 



One agency of surprising effectiveness, although com- 

 pletely ignored by Laplace, was undoubtedly concerned. 

 In his " Naturgeschichte " (1755), Kant threw out the 

 idea that the moon's rotation was slowed down into 

 correspondence with its rate of revolution by the 



