ytme 27, 1872] 



NATURE 



165 



wide distribution, extending from the mountain valleys 

 and neighbouring plains to the edge of the glaciers ; 

 very few being found only in tlie mountain valleys, 

 and one only, the common honey-bee, being peculiar to 

 cultivated districts. None of the insects found belongto 

 extra-Alpine species, none of the kinds peculiar to the 

 warm valleys of the southern Alps are represented ; and 

 the inference is unavoidable, that all the animals found 

 on the glaciers have either strayed voluntarily, or have been 

 driven by the wind, from districts immediately adjacent 

 to the glacier. 



The task of determining the seeds found on the sur- 

 face of the glacier was much more difficult. The seeds of 

 many Alpine plants have hardly been described ; and in 

 other instances it is difficult to distinguish between those 

 belonging to several different species of the same genus. 

 Thirty-six species, however, were determined with 

 tolerable certainty, the majority of which were identical 

 with the species previously recorded as inhabitants of the 

 moraines. Here ag.ain the same results are established : 

 not a single seed is found on the glacier, as not a single 

 plant on the moraine, which does not belong to a species 

 inhabiting the immediately adjacent mountain slopes or 

 valleys. The conclusion from these facts seems inevitable, 

 that the conveyance of seeds, even when provided with 

 apparatus calculated for being floated in the air by hori- 

 zontal currents, takes place only within very circumscribed 

 limits ; and that the prevalent opinion that they may be 

 thus carried for very great distances is not supported by 

 facts. 



M. Kerner thus sums up the results of his observa- 

 tions : — 



1. Only dust-like substances, such as pollen, spores, 

 diatom-scales, &c., can bs distributed by currents of air 

 over wide stretches of land and sea in uninterrupted 

 flights, and thus be brought into the alpine regions. 



2. Fruits and seeds of flowering plants which are pro- 

 vided with a web-like floating apparatus that distends 

 itself in dry air in the form of a parachute, are carried 

 upwards by the ascending current of air which arises on 

 sunny days in alpine regions on the cessation of the 

 horizontal wind ; but after sunset they sink again to the 

 ground at a short distance in a horizontal direction ; and 

 the object attained by this floating apparatus is not so 

 much the adaptation of the seeds for long journeys, as to 

 enable them to settle on the projections and in the 

 crevices of steep precipices and rocks, and to clothe with 

 vegetation these rock-walls which are not easily accessible 

 by other seeds. 



3. The presence of membranous margins and wings 

 favours the transport of fruits and seeds by horizontal 

 currents of air ; the horizontal distance, however, over 

 which these seeds are carried scarcely ever extends farther 

 than from one side of a valley to the other, and the dis- 

 tribution of the fruits and seeds of flowering plants, in so 

 far as this is caused by currents of air, can only proceed 

 gradually and step by step. 



4. Fruits and seeds which are deficient in any kind of 

 appendages that facilitate flight are scarcely influenced 

 by currents of air ; it is only when these seeds are of very 

 minute size and extremely small weight that they can be 

 driven short distances by horizontal winds. 



It app'-irs, therefore, that the idea that seeds are dis- 

 tri'.j-ited to great distances by the wind, if not to be treated 

 as a popular error, at least requires a much larger founda- 

 tion of fact than it at present possesses, in order to be 

 accepted as a scientific truth. A series of observations 

 of this nature, if carefully conducted, is a substantial gain 

 to Science, and may assist the determination of great 

 physiological questions in hundreds of ways. They are 

 within reach of every intelligent resident in the country 

 possessed of ordinary powers of observation ; and yet 

 how few interest themselves practically in carrying them 

 out ! A. W. B. 



LY ELL'S PRINCIPLES OF GEOLOGY* 



IN o\ir last notice, after a sketch of the methods of 

 investigation employed by Sir Charles Lyell, and an 

 outline of the principles deduced therefrom, we gave a 

 few examples of the kind of proofs brought forward by 

 him to show that the degrading and transporting forces 

 which we see in operation are producing similar pheno- 

 mena to those we obser\e in the sedimentary rocks, and 

 that, given sufficient time only, effects on as great a scale 

 must be the inevitable result. 



We will now select some of the evidence adduced by 

 him to show that the igneous forces also, the movements 

 of upheaval and depression, are as active, and the pro- 

 ducts of eruption on as grand a scale, as we have any 

 reason to believe they have ever been within the period 

 over which our observations extend. 



The consideration of what suggested the former greater 

 intensity in the subterranean forces, viz., the supposed 

 vast magnitude of the ancient igneous rocks, and the 

 proofs of variations in climate, leads Sir Charles into an 

 investigation of the astronomical and geographical causes 

 of vicissitudes of climate, which involves an inquiry into 

 the ve.xed questions of oceanic circulation, and the effect 

 of various changes of conditions on the organic world in 

 the extinction of species, and their replacement by new 

 forms of life. 



It certainly may at first seem difficult to believe that 

 the forces which produce upheaval and eruption have 

 not varied in intensity throughout the whole period of 

 which we have any record, and yet that over many large 

 tracts of country, where now the faintest vibration of the 

 distant earthquake is exceptional and rare, we have 

 thousands of feet of volcanic ash and lava, and great 

 masses of matter which have apparently been injected in 

 a molten state into' the fissured rock. But this difficulty 

 has arisen because the vastness of the ancient volcanic 

 deposits has been assumed without sufficiently detailed 

 observation, and the magnitude of modern igneous action 

 has been underrated, while the most important point, the 

 transference of paroxysmal action from one area to 

 another, has been overlooked. 



Speaking of contemporaneous volcanic deposits in the 

 older rocks. Sir Charles Lyell says : — " If one of these 

 igneous formations is examined in detail, we find it to be 

 the product of many successive ejections or outpourings 

 of volcanic matter. As we enlarge therefore our know- 

 ledge of the ancient rocks formed by subterranean heat, 

 we find ourselves compelled to regard them as the aggre- 

 gate effects of innumerable eruptions, each of which may 

 have been comparable in violence to those now ex- 

 perienced in volcanic regions " (p. 1 14). This question, 

 however, Sir Charles does not investigate in the " Prin- 

 ciples," which deals with the modern changes of the 

 earth ; and we will pass on to notice some of the ex- 

 amples he gives to show the magnitude of modern 

 igneous action. 



First, as to the fact that changes of level are going on : — 

 " Recent observations," says Sir Charles Lyell, " have 

 disclosed to us the wonderful fact that not only the west 

 coast of South America, but also other large areas, some 

 of them several thousand miles in circumference, such as 

 Scandinavia, and certain Archipelagos in the Pacific, are 

 slowly and insensibly rising ; while other regions, such as 

 Greenland and parts of the Pacific and Indian Oceans, 

 in which circular or coral islands abound, are as gradually 

 sinking" (p. 12S). The atolls are themselves a proof of 

 oscillations of level. The coral zoophytes live only with- 

 in certain distances from the surface, and, having com- 



* " The Principles of Geolog>', or the Modern Changes of the Earth and 

 its Inhabitants considered as Illustrative of Geology." My Sir Charles 

 Lyell, liart. Eleventh and entirely revised edition. (London : J. Murray, 

 1S72.) (The Second Volume has been issued since the tippcnrance of our 

 last notice ; see Nature v. p. 456.) 



