426 



NATURE 



[Augtcsi 28, 1879 



by their irregularity, that all organic origin is excluded, some- 

 times in ice ; they originate in the hardening together of crystals, 

 under pressure, and are only the imprisoned, often stem-like and 

 branded hollows of air. Uke Eozoon they become afterwards 

 filled with foreign matter, with serpentine and chrysotile, re- 

 sulting out of the watery decomposition of olivine. 



To show how analogous circumstances are also applicable 

 to the origin of Eozoon, I shall first refute the two erroneous 

 arguments often adduced for the organic existence in the lauren- 

 tian period : the presence of graphite and the stratification of 

 the oldest rocks. 



Graphite, as Dr. Moebius supposes, cannot be a sign of primi- 

 tive organic life, (i) In the oldest period there certainly lived 

 only the most primitive lower beings, which without exception 

 decay rapidly, and are therefore not able to furnish coal. (2) 

 Graphite is sometimes a substitute of mica in the Gneiss ; if 

 it be phytogen, the synchronous quartz and feldspar, &c., 

 must also be declared so ; but that is absurd. {3) We always 

 get amorphous coal out of organic beings, and by chemical 

 process in the cold way, and on the contrary crystaUised coal, 

 i.e. graphite, is only to be produced by heat, and in several 

 ways, even out of gases. We must regard graphite as one of 

 the arguments, proving the incandescent origin of the oldest 

 rocks. Out of each kind of coal, also of graphite, bitumen can 

 originate, so that bitumen is not always a sure proof of organic 

 beings. (4) There exist many other facts proving the incan- 

 descent origin of laurentian minerals ; I will add, as I believe, a 

 new one. This origin excludes at the same time any living 

 beings. Not one original mineral of the laurentian minerals 

 contains water, only mica contains a very small proportion, but 

 this chemically combined, for it cannot be expelled at red heat. 

 If these minerals had not had their origin in heat, they would 

 sometimes contain water. 



The other fallacious proof for the neptnnic origin of laurentian 

 rocks is their occasional stratification, and this origin would in- 

 clude the possibility of organic beings. No geogenetic hypo- 

 theses have been able to combine the facts of heat origin and 

 stratification ! But if we change the generally adopted opinion 

 of Kant and Laplace, that the gases of the atmokosmos formed 

 our globe by being condensed first into incandescent liquids, and 

 finally into crystals, we may combine all the facts. 



It is often found that we get out of hot gases mostly 

 crystals, which partly by chemical reaction, become at first in- 

 candescent, and even quartz, feldspar, granite, and some iron 

 minerals that we find in the granite, are known to be produced 

 crystallised out of gases. Other facts prove that these laurentian 

 minerals must have originated between white and red heat. 



In the origin of glaciers we have an analogy for the agglome- 

 ration of the incandescent crystals into the first earth-crust without 

 melting, only by baking together, as being somewhat plastic, the 

 crystals of snow harden together into ice, driving out the air 

 between the crystals and loosing their crystallised surface, 

 assuming also sometimes Eozoon-Iike forms. Glaciers not seldom 

 show stratifications, especially in the upper part formed by tem- 

 porary snow-falls. As on the top of the glacier the snow-crystals 

 lie yet ununited, so the minerals of the laurentian period were 

 certainly lying ununited upon the surface, and became afterwards 

 hydrated together, when the earth-crust was cool enough, so that 

 we find them in the post-laurentian period much more mixed and 

 with products of neptunic erosion. Otto Kuntzk 



Leipzig-Eutrifzsch, August 2 



Unobserved Impressions 



A NOTE to Mr. Mivart's address in the Biological Section of 

 the British Association contains the following : — 



" Having gazed vacantly through a window we revert to the 

 pages of a manuscript we may be writing and see there the 

 spectra of the window bars we had before unconsciously seen. 

 Here the effect on the organism must have been similar to what 

 it would have been had we attended to it — »>., it was unfelt 

 sensation " (Nature, vol. xx. p. 399). 



The last words induce me to mention what I believe I have 

 often observed but have hitherto presumed to be well known 

 in psychophysics, because though they are not inconsistent w ith 

 it they seem to show that it had escaped the speaker ; namely, 

 that an unobserved impression produces a much stronger effect 

 on the organism immediately impressed than an observed im- 

 pression. Of course the observation cannot be experimentally 

 prepared; but if any one who experiences a case like that 



described by Mr. Mivart will allow the image to fade and then 

 try to form another of the kind, he will be struck I believe by 

 the inferiority of the voluntary one. 



Tlie phrase "unfelt sensation" suggests questions I wish to 

 keep clear of ; but the phenomenon appears to me interesting, 

 because it plainly shows that work which would be done on the 

 retina, or on something, by an unobserved impression, is done 

 elsewhere by an observed one. C. J. Monro 



Chesterfield, August 24 



Insect-Swarms 



A WONDERFUL flight of insects has passed over here to day, 

 consisting of the butterfly V. cardui and the moth P. gamma. 

 They all came from the sea from the north-west and passed over 

 the land to the south-east. I first noticed the flight at 7.30 A.M. 

 The morning was bright and sunny with a light wind a little 

 south of east. Great numbers of V. cardui were soaring at all 

 heights, up to at least 150 feet, above and between the poplars 

 w hich surround the house in which I am staying ; all were going 

 leisurely to the south-east ; lower down P. gamma more erratic 

 in its flight, was going in numbers in the same direction. I went 

 down on to the grassy slope above the shore cliff". The black- 

 berry blossoms were covered with V. cardui and P. gamma, 

 three or four on a flower, the fussy moths much disturbing the 

 more sedate butterflies, but each bent on holding its ow'n. Wi!' 

 scarcely an exception they took flight in a south-east direct! 

 when disturbed or when satisfied with their often, I fear, va: . 

 search for food. I stepped fifty paces from a clump of dark fiix 

 at right angles to their line of flight and counted the butterflies 

 which passed for two intervals of two minutes ; the numbers 

 were 95 and 108, but I probably missed some of the higher 

 ones. On the shore at 10 o'clock I counted 73 in one minut'; 

 pass a space 50 paces in width ; at 1 1.45 in one minute 50 pass eil 

 the same space. The numbers oi P. gamma were more difiicul'- 

 to ascertain owing to their smaller size and more erratic flight, 

 but as they all flew very low on the shore, not more than a 

 foot or two at most above the water or sand, I stepped 20 paces 

 and tried to count the moths passing within those limits with the 

 result — one minute 32 moths, two consecutive minutes 18 moth.-, 

 again two minutes 120 at least. In the second interval a strong; 

 gust of wind checked the flight altogether, and in the thirvl 

 interval the moths came so fast that I missed many I feel sure. 

 The P. gamma were evidently much exhausted ; while bathing ! 

 saw several floating on the surface of the water, which tool; 

 flight when touched or crawled on to a finger presented to them ; 

 some settled on me and on others while we were bathing. At 

 12 o'clock I passed uninterruptedly through the flight whilo 

 walking from Trouville Harbour for a distance of two kilometres 

 northwards along the shore. There was then an occasional 

 white butterfly (Pieris) in the flight, and I also noticed two 

 dragon-flies coming from the sea and following the same direc- 

 tion as the other insects ; I noticed other dragon-flies vi'ith the 

 flight inland, but they abound here. Had those coming from 

 the sea accompanied the flight throughout as hawks are said to 

 follow the flights of birds on which they prey? From th<.' 

 shore I climbed up the cliff, the grassy slopes above it were 

 swarming with P. gamma and V. cardui, nearly every flower 

 having one visitor at least. At 1. 15 P.M. P. gamma passed 

 over in undiminished numbers, but V. cardui was not so 

 abundant. At 5.30 I rode parallel with the coast line along 

 the Honfleur road to a point rather more than 10 kilometres 

 from Trouville, passing through an uninterrupted flight of P. 

 gamma all the way, but no V. cardui, though the butterfly stil.' 

 abounded on the blackberry and other blossoms by the road- 

 side. Throughout the last two kilometres the moths were much 

 fewer in number, but had not quite disappeared when I turned 

 back. P. gamma generally flew lower than V. cardui, but 

 the force which impelled them in one direction, as if their 

 bodies were magnetised and their north pole was in the south-east, 

 was so strong that when they met an obstruction to the course of 

 their flight they went often over it not round it. While riding 

 I noticed that they rose up and flew over isolated buildings, and 

 I was curious to see whether they would do the same with a 

 church tower. As I passed through Villerville, three came over 

 the top of the church tower, and again at Criquebceuf, three 

 fluttered up the wall, and flew over the church tower as I passed 

 it. At 8 p. M. I went up on to the roof of the house ; the moths 

 were then flying up the front of the house and over the roof in 

 great numbers. The flight of P. gamma continued to pass the 



