26 



HARDWICKE'S SCIENCE-GOSSIP. 



from a variety, changes so complete, irregularities 

 though they be, that eventually become constant. 

 This is all that is required to constitute a distinct 

 species. Can we not then imagine the heart's-ease 

 becoming gradually much smaller as regards the 

 flower ? Added to this, can we not imagine the 

 eolour of one variety settling down to a soft blue or 

 purple ? Nay, have we not this latter already very 

 abundant ? Can we not imagine the violet being 

 what I may call a confirmed variety of the pansy, a 

 heart's-ease? 



There is a beautiful little yellow flower which every- 

 body knows — I mean the cowslip. This belongs, 

 according to Linnaeus, to Primula. Everybody is 

 aware of its beautiful orange colour. Suppose, in 

 the propagation of this species of the genus Primula, 

 something should cause the colour to vary ; wc will 

 say from the darker yellow to a light pale colour. 

 What then? you would say, you have frequently 

 seen one cowslip of a paler yellow than another. 

 But by this simple action, freak, if you will, of 

 nature, we get a variety, the light or pale cowslip. 

 This will be the colour of the primrose. But further, 

 the cowslip has several flowers on one stalk. I 

 suppose in one case it has eight flowers on one stalk ; 

 and in another, six. The mixture of these two 

 varieties, what would it produce ? It might be more 

 than eight flowers to one stalk, it might be less than 

 six. If it be less, this might be crossed with another 

 containing but four flowers on one stalk. What 

 ■would be the production ? Thus this crossing system 

 might continue until in some cases the number of 

 flowers on a stalk should be reduced to one. What 

 then ? Still remembering the variety of colour which 

 is now pale, we shall have a cowslip of a pale yellow 

 colour, with but one flower to a stalk. But this is 

 a primrose. May not a cowslip thus become a 

 primrose ? 



I will not say that all species of plants have origin- 

 ally been produced from one common stock by this 

 law of variation — I will not say that from a few 

 species have sprung all the immense numbers of 

 distinct species of plants that we know of, through 

 this law — but I will say that the evidence tends to 

 prove that this action of nature produces species. 

 1 will say it is a powerful agent of nature, causing 

 some flowers to become so diverse in their character 

 that we know not how to treat of them but as distinct 

 species, and this to our knowledge. And I will 

 further say that a future day will in all proba- 

 bility prove the mighty power of the action of a great 

 law, which we have called the law of variation, and 

 then shall be demonstrated, what at present may 

 not be quite so obvious, that species, in their pro- 

 pagation, tend to produce other species like them- 

 selves, but through many causes varieties are often 

 produced, whose differences from the original stock 

 are ultimately confirmed in themselves, and hence 

 arise new species. 



THE PEBBLE-BED OF THE LOWER 

 GREENS AND OF GODALMING. 



^TOW that the existence of a ridge of ancient 

 ^ rocks, so long believed by geologists to cross 

 the south-east of England somewhere in the neigh- 

 bourhood of London, has been fairly proved (thanks 

 to Messrs. Meux & Co.'s boring in the Tottenham 

 Court Road), it may not be altogether uninstructive to 

 point out certain ancient submarine detrital beds, the 

 wreck of older rocks which once covered the Devonian 

 bids, the weathered surface of which was struck upon 

 in the Tottenham Court Road, and which probably 

 still flank the ancient crest to the north and south. 

 These detrital beds, which abound in water-worn 

 pebbles and fossils, both apparently derived from 

 lower secondary rocks, occur around Godalming at the 

 base of the Folkestone, or upper division of the lower 

 greensand, and consequently between the Bargate 

 stone beds and the upper sand beds of the middle 

 division, sometimes alternating with the lower bands 

 of Bargate. Passing over a few Brachiopoda, and 

 two or three species of Pecten and Exogyra, which 

 are in very much the same state as when first left by 

 the sea: "The whole," says Mr. Meyer, "would 

 appear to be extraneous (Oolitic and Liassic) fossils 

 which had been drifted into the present position at 

 the time of the deposition of the strata in which they 

 now occur."* Unlike the proper fossils above 

 mentioned, the extraneous ones are mostly of a rich 

 brown colour, and frequently much water-worn, 

 although examples may be often found in almost 

 perfect condition. Among them wc have the small 

 pretty Ammonites Lamberti and A. crenatus of 

 the Oxford jday, together with several other species, 

 as likewise casts of small univalves and bivalves, 

 which have not yet been identified, and also teeth 

 and scales of saurians, and teeth of fishes ; to these 

 I shall refer again in the sequel. Speaking of these 

 fossils Mr. Meyer says, "The fact of their occurring 

 in any condition in the lower greensand of this district 

 is of considerable interest. For if, as appears to be 

 the case, they are really drifted fossils, it is clear that 

 the rocks from whence they were derived cannot have 

 been far distant from the places where these fossils 

 are now found. And it must be remembered that 

 teeth of the genus Saurichthys, of which two, if not 

 three, specimens occur in the pebble-beds, are not 

 known to occur elsewhere in England in beds 

 younger than the Triassic bone bed of Aust cliff and 

 Axmouth." There is one fact in connection with the 

 pebble-beds which I think is worthy of note. I am 

 willing to admit, however, that the pebble-bearing 

 beds are apparently always evenly bedded ; but their 

 coarse nature renders it difficult to speak with absolute 

 certainty. The finer sand beds alternating with them, 



* For this and much of the following, I am indebted to a 

 paper on the " Lower Greensand of Godalming," by C. J. A. 

 Meyer, read before the Geological Association, Dec. 4, 1S68. 



