HARDWICKE'S SCIENCE-GOSSIP. 



245 



with its mode of occurrence, which help us in forming 

 an opinion regarding its mode of origin. In the 

 first place, it only occurs on the seaward side of 

 the wolds, entering the Steeping valley and the east 

 fens as if it would if it were a coast deposit, and these 

 were bays in the coast-line of the period. Again, 

 the beds of sand and gravel which occur in and 

 underneath the clay frequently contain sea shells like 

 those now living on the coast. Finally, it would 

 appear that the boulder clay is banked up against the 

 chalk hills to a depth of 40 or 50 feet in some places, 

 and that if we could strip it all away we should find 

 a steep scarp or cliff of solid chalk, like the cliffs of 

 Flamborough Head, only not quite so lofty. These 

 buried cliffs begin at Welton-le-marsh, and pass a 

 little west of the following places— Well, Rigsby, 

 Belleau, Muckton, Cawthorpe, and Louth (see map) ; 

 and probably northward to the Humber. 



For these and other reasons it is believed 

 that the Hessle boulder clay has been pro- 

 duced by the action of coast-ice against the 

 Lincolnshire shore. In order therefore to 

 realise the physical conditions which pre- 

 vailed at the time when it was being formed, 

 we must read the descriptions given by 

 those who have sailed in Arctic seas, or 

 have visited the northern shores of the 

 American continent. They tell us that the 

 freezing of the sea round the coast produces 

 a shelf of ice, many feet high and sometimes 

 a hundred feet broad, which is called the 

 ice-foot, this clings to the coast all the 

 winter, and from the steeper parts of the 

 shore tons of rock rubbish fall upon its 

 surface, while outside its edge icebergs and 

 loose sheets of ice float in the sea. When 

 spring-time comes great storms arise which 

 loosen the ice-foot and break up the floes 

 outside, driving the latter against and on 

 to the former ; in this way great masses of 

 ice are often piled up against the coast, and 

 where the shore is sloping these are often 

 driven far into the land, crashing and 

 grinding over the rocks of which it is com- 

 posed. After the storms comes a brief but 

 warm summer, the masses of ice begin to melt under 

 the sun's rays and the mud and stones with which 

 they are loaded are left in the shallows along the 

 shore ; the upper portion of this material is drifted 

 and sifted by the tidal currents, but the greater part 

 probably remains as an unstratified boulder clay. 



( To be continued.) 



Why Flowers turn White. — Could any of 

 your readers explain the reason of some flowers 

 turning white, such as the foxglove, when brought 

 into a garden ? — M. F. 



A PECULIAR AMOEBA. 



TWO years ago I obtained some water from a 

 pond, in which, among other things, I found a 

 very beautifully coloured Amceba, a copy of which I 

 enclose. Having never seen any before like it, nor 

 any description of such an one, I drew a sketch of it 

 at the time. The general colour of the creature was of 

 a very light bluish tint, very transparent, and the 

 granules, of which there was a great number, were of 

 a brilliant gold colour, the contrast of colour render- 

 ing it a very beautiful object. On reading Professor 

 Allman's address, delivered May 24, 1876, at the 

 anniversary of the Linnean Society, the subject of 

 which was ' ' On recent researches among some of 

 the more simple sarcode organisms," I there find 

 the following description of an Amoeba, illustrated 

 by a drawing, which appears to answer to the one 



Fig. 180.— Peculiar Amceba (Dactylosfiluzruim vitreum ?J. 



mentioned : — " Under the name of DactylospJuerium 

 vitreum, Hertwig and Lesser describe a freshwater 

 rhizopod which but slightly differs from Amceba. It 

 has a roundish body composed of homogeneous 

 hyaline protoplasm with a multitude of yellow or 

 green strongly refrangent granules, which fill the 

 whole of the interior of the body as far as a narrow 

 hyaline margin. The pseudopodia are blunt finger- 

 shaped processes which radiate in all directions from 

 the surface, and consist of a perfectly homogeneous 

 hyaline protoplasm. The mode in which the pseu- 

 dopodia are withdrawn is peculiar. When one of 

 these is about to disappear, it seems suddenly to 

 change its form ; its smooth surface becomes nodular 



