August 25, 189SJ 



NATURE 



403 



and rises into many green columns. In wet or cloudy weather 

 the wings open wide, but when the sun shines they fold over 

 the columns, and protect them from scorching. 



All the most characteristic plants of the moors are Arctic. 

 Ling, bilberry, crowberry, certain rushes, Nardus, Festuca 

 ovina, most of our club-mosses, the hair-moss, and Sphagnum 

 range within the Arctic Circle ; while the large flowered Heaths 

 get close up to it. -Most of them are found on both sides of the 

 Atlantic, and some, like the crowberry and Festuca ovina, have 

 a singularly wide distribution. 



It has often been pointed cut that great elevation above sea- 

 level produces a similar effect upon the flora to that of high 

 latitude. In the Alps, the Pyrenees, the Himalayas, and even 

 in the Andes, the forms characteristic of northern lands re- 

 appear, or are represented by allied species. Where, as in the 

 case of the Andes, nearly all the species differ, it is hard to draw 

 useful conclusions, but whenever the very same species occur 

 across a wide interval the case is instructive. In the Alps we 

 find our moorland and arctic flora almost complete, though 

 Rubus Chamcemorus, Erica Tetralix, and E. cinerea (both 

 found in the Pyrenees), Narthecium ossifragum and Aira 

 flexuosa have disappeared. 



A favourite explanation rests upon the changes of climate to 

 which the glaciation of the northern hemisphere bears emphatic 

 witness. When the plains of Northern Europe were being 

 strewn with travelled boulders, when Norway, Scotland, and 

 Canada were covered with moving ice, the vegetation of 



2. — Transverse section of leaf of Festuca ovina. In thick sections 

 hairs are seen to point inwards from the inner epidermis. 



Siberia and Greenland may well have extended as far south as 

 Switzerland. 



I do not doubt the general truth of what we are taught re- 

 specting the glacial period, but I think that we are apt to ex- 

 plain too much by its help. We know very little for certain as 

 to its effect upon vegetation. Our information concerning the 

 preglacial flora is extremely meagre, nor are we in a position to 

 say positively what sort of flora covered the plains of Europe 

 after the severity of glacial cold had passed away, and before 

 men had changed the face of the land by tillage.^ We know 

 rather more about the animals of these ages, for animals leave 

 more recognisable remains than plants, but the indications of 

 date, even in the case of animals, are apt to be slight and un- 

 certain. On the whole, I doubt whether the glacial period 

 marks any great and lasting change in the life of the northern 

 hemisphere.'^ I think it probable that since the glacial period 

 passed away the countries of Central Europe possessed many 

 species both of plants and animals which we should now con- 

 consider to be Arctic, and that these Arctic species endured 

 until many of them were driven out by an agent of which geo- 

 Ic^ists usually take little notice. I shall come back to this point. 



The animal life of the Yorkshire moors is not abundant. 



1 Some information has been gained by investigation of plant-remains 

 found beneath the bogs of Denmark, and beneath the palaeolithic brick-earth 

 at Hoxne. 



2 It is well known that this position has been strongly maintained by 

 Prof. Boyd Dawkins (" Early Man in Britain," p. 123, &c., Q. J. Geol. 

 Soc, vol. XXXV., p. 727, and vol. xxxvi., p. 399). On the other side, Dr. 

 James Geikie may be consulted (" Prehistoric Europe," ch. iii.,&c.). 



NO. 1504, VOL. 58] 



Hares, shrews, stoats, weasels, and other small quadrupeds, 

 which are plentiful on the rough pastures, cease where the 

 heather begins. There are a good many birds, some of which, 

 like the grouse, the ring-ouzel, the twite, or mountain-linnet, 

 the curlew, and the golden plover, seek all their food on the 

 moor, except in the depth of winter, when some of them may 

 visit the sea-coast, or the cultivated fields, or even southern 

 countries. The kestrel, blackbird, whinchat, stonechjtt, night- 

 jar, and lapwing abound on the "roughs" or border-pastures 

 rather than on the moor itself. Owing to the absence of tarns 

 and lochs there are practically no waterfowl. Gulls are hardly 

 ever seen, though they are common enough on the Northumber- 

 land moors. Now that the peregrine, golden eagle, and hen- 

 harrier are exterminated, the chief moorland birds of prey are 

 the merlin, kestrel, and sparrowhawk. Of these only the merlin 

 is met with in the wilder parts of the moor, where it flies down 

 the smaller birds. The kestrel hovers over the roughs, on the 

 look-out for a mouse or a frog. The sparrow-hawk preys upon 

 small birds, but rarely enters the heait of the moor. 



To most people the interest of the moor centres in the grouse. 

 There are many things about grouse which provoke discussion, 

 such as its feeding times, or the grouse-fly, and what becomes of 

 it during the months when the grouse are free of it. But the 



Fig 13.— Transverse section of stem of Rush {/uncus conglomeratus), 

 showing the stellate pith-cells, and very numerous air-spaces. 



absorbing topic, on which every dweller by the moor is expected 

 to have an opinion, is the grouse-disease. 



All sorts of causes have been assigned, such as over-stocking 

 of the moors, destruction of the large hawks which used to kill 

 off" ailing birds, parasitic worms, cold, deficiency of food, and 

 so on. Some Yorkshire sportsmen have attributed the disease 

 to the scarcity of gritty sand. On shale-moors, they maintain, 

 the gizzard of the grouse is filled with soft stones, which will 

 not grind up the heather- tops efl'ectively, except when they are 

 young and tender. On sandstone moors the grouse can deal 

 with tougher food, and there the disease, it is said, is unknown. 

 Dr. Klein's researches* show that the disease is really due to 

 the multiplication within the body of a specific germ, which is 

 fungal, but not bacterial. The infection is conveyed, or may be 

 conveyed, by the air. 



The viper is rare, and until quite lately I had never heard of 

 its presence on our Yorkshire moors. Lizards are also rare, but 

 efts are not uncommon. Among the moorland moths are many 

 small Tineina (allied to the clothes-moth). The caterpillar of 

 the emperor moth is characteristic, and seems to be protectively 

 coloured, for it wears the livery of the heather — green and pink. 



1 " The Etiology and Pathology of Grouse Disease, &c." (1892). 



