December 17, 1891J 



NA TURE 



151 



My reason for suggesting such an origin for the migration is 

 that it takes place every three or four years from the same 

 plateaux. It is very evident, therefore, that — abiogenesis 

 being now out of court — some lemmings must be left there to 

 continue the species. Now, it is not likely that the weakest are 

 left behind, otherwise their survival year after year would be 

 quite problematical. Do not the facts point unquestionably to 

 the strongest being left to continue the race ? 



To the criticism that there is no evidence of fighting having 

 taken place amongst the migrants, my reply would be that no one, 

 so far as I can learn, has seen a migration start, or seen one 

 immediately after it has started — the only time, that is, when 

 the effects of such fighting would be apparent, for after a few 

 days those seriously injured would have died and have been left 

 behind, while those only slightly injured would have recovered 

 sufficiently to be indisiinguishable from the remainder. 



Churchfield, Edgbaston. F. Howard Collins. 



The New Railway from Upminster to Romford, Essex. 



On the above railway, now being constructed, there is a sec- 

 tion of unusual interest a few yards north-east of the church at 

 Hornchurch, showing the Chalky Boulder Clay (15 feet seen) 

 under sand and gravel belonging to the highest terrace of the 

 Thames Valley, and resting on London Clay. Hitherto, 

 Boulder Clay has not been seen in this district in connection 

 with Thames Valley deposits, its most southerly exposures lying 

 about three miles northward, on London Clay or Bagshot Beds. 



I have been carefully watching this cutting for some time, 

 with a view of sending an account of it to the Geological Society 

 when it shall have been completely excavated. But, though 

 much has still to be done, the half of it finished has already 

 been sloped, and the arrangement of the beds — clear a month 

 ago — greatly obscured. It has therefore been suggested to me 

 that a few lines on the subject in Nature may be the means 

 of enabling geologists interested to visit this section while the 

 Boulder Clay is still clearly visible in some portion of the 

 cutting. 



It may be useful to add that the distance from Hornchurch 

 Station is about a mile, and that the visitor, after leaving the 

 church on his right hand, should take the first road on his left. 



T. V. Holmes. 



28 Croom's Hill, Greenwich Park, S.E., 

 December 7. 



as it were, whatever it is that constitutes the individuality of the 

 stock. The phenomena presented by parasitic plants seem to 

 bear out this view. W. H. Beeby. 



Peculiar Eyes. 



The inability of keeping one eye shut and the other open at 

 the same time, is a fact well known to drill-sergeants. I well 

 rt member, when a conscript some sixteen years ago, how a great 

 number of recruits were unable, even after repeated efforts, to do 

 so ; but I had no difficulty about it. At that lime, too, my 

 eyes were about equal in power ; but at present while the 

 ri^ht eye is of normal power, the left eye presents a much less 

 distinct image. I can only ascribe this to the habit of working 

 at the microscope with the right eye without closing the left. 

 It is especially at this work that the defective sight in the latter 

 is noticeable. I do not think my ten months of rifle practice has 

 anything to do with it, except, perhaps, in emphasizing the 

 tendency to use the right eye, the image of which is now so pre- 

 dominant, that in covering a bull's eye, for instance, it is 

 immaterial whether the left eye be closed or not. 



G. K. GUDE. 



S Giesbach Road, Upper Holloway, December 7. 



Grafted Plants. 

 Referring to Prof. Henslow's paper on "A Theory of 

 Heredity based on Forces " (November 26, p. 93), the behaviour 

 of grafted plants seems to require, for its explanation, the pis- 

 session by both stock and graft of something analogous to a 

 distinct individuality, call it what we may. It is difficult enough 

 to understand, especially in the case of nearly-related forms, 

 why the stock generally has no, or so little, influence on ihe 

 graft ; but, assuming the absence of individuality, the difficulty 

 is largely increased. The graft takes its nourishment through 

 the stock, and yet retains its characteristics unimpaired. I argue 

 from this that not only does the graft possess an individuality of 

 its own, but that this is so marked that it can take its nourish- 

 ment direct from the stock, while at the same time straining out, 



NO. II 55, VOL. 45] 



Intelligence in Birds. 



A FEW weeks ago I received a specimen of Podoces panaeri, 

 the typical desert bird of Central Asia, which had been kept 

 for some months in captivity at Perowsk. The first thing the 

 creature began to do, when located by me in a spacious voliere, 

 was to pick some food (cooked rice with baked egg>), and to 

 bury it in the very thick sand layer with which the floor of 

 the cage was provided. This was the incessant occupation of 

 the bird on the first day of its instalment. But the task was 

 almost completely abandoned from the next day ; the bird, evi- 

 dently remembering the conditions of its former life in captivity, 

 found it useless to make provision for the future when a fresh 

 supply of food daily appeared. 



The fact referred to seems to indicate, first, that the birds in 

 question are in the habit of making provision in the wild state, 

 the powerful and slightly curved bill being admirably adapted 

 for the purpose of making holes, even in a hard ground. It 

 shows, also, how abruptly the habits of animals can be modified 

 when the conditions of their environment are changed. 



Now, a question naturally arises, How must we regard this 

 habit of burying food — as the result of a long inheritance, or as 

 an effect of constant imitation of older birds by younger ones? 



A. WiLKINS. 



Tashkend, Central Asia, November 8/20. 



SIR ANDRE IV CROMBIE RAMSAY. 



'THROUGH this illustrious geologist has been laid aside 

 ■'■ by growing infirmity for the last ten years, the news 

 of his death will carry regret into the hearts of many men 

 of science, not in this country only but all over the world. 

 Born in Glasgow, and intended for a mercantile pro- 

 fession there, he spent some few years in business ; but, 

 partly on account of delicate health, betook himself for 

 rest and open-air exercise to the island of Arran. One of 

 the friends of his early years, Prof. Nichol, of Glasgow 

 University, the well-known writer on astronomical sub- 

 jects, had much influence in directing his studies into a 

 scientific channel, so that the marvellous geological 

 lessons to be learnt from the rocks of Arran soon arrested 

 Ramsay's attention. Throwing himself with all the ardour 

 of an enthusiastic nature into the pursuit which he now 

 took up, he was led to climb the mountains and traverse 

 the glens throughout the length and breadth of Arran. 

 In this way, face to face with the facts of Nature, and 

 amid some of the most charming scenery of his native 

 country, he taught himself the rudiments of geology, and 

 acquired that clearness of insight for geological structure, 

 that love of mountain-forms, and that freshness and origin- 

 ality of interpretation, which marked him out from his 

 associates in later years. But above all, by actually 

 mapping the grouping of the rocks, he gained that pre- 

 cision in field-work which was to bear such notable Iruit 

 in his connection with the Geological Survey. He con- 

 structed a geological model of Arran on the scale of 

 two inches to a mile, and made copious notes of the 

 geological structure of all parts of the island. 



The meeting of the British Association in Glasgow in 

 the year 1840 proved to be the turning-point in his career. 

 The model and map of Arran which he had made were 

 exhibited at the Geological Section, and he gave a brief 

 account of them and of the geology of the island. Among 

 the geologists who listened to him was Murchison, who, 

 struck with his ability and his devotion to the science, 

 offered to take him on an expedition which the author of 

 the "Silurian System" had then projected to America. 

 Ramsay accordingly went up to London, but found that 

 the voyage across the Atlantic had been abandoned for a 

 journey into Russia, and that he was not to take part in it. 

 Murchison, however, spoke so warmly in favour of his- 



