194 



* KNOWLEDGE ♦ 



[Sept. 28, 1883. 



commons of Kent and Surrey, where the prickly variety of 

 common rest-harrow alone can thrive ; the more ordinary 

 armed variety is all eaten down wherever it appears by 

 the ubiquitous London donkey. The leaves of the stone- 

 bramble are divided into three leaflets, after a fashion 

 which runs more or less throughout the whole genus ; and 

 the flowers are in a sort of intermediate stage between 

 dirty greenish-yellow and dingy yellowish-white. The red 

 berries do not difl'er much, except in the fewness of the 

 carpels, from those of the raspberry. 



In the higher brambles — the raspberry, blackberry, and 

 dewberry — we get the same type still further developed 

 into a straggling woody bush. This growth in woodiness 

 depends, of course, merely on the thickening and length- 

 ening of certain cells and cell-walls in the stem, and it 

 is everywhere readily produced by natural selection, 

 W'herever the circumstances are favourable to its evolu- 

 tion. Yet the difference between the stone bramble and 

 the raspberry in this respect is far less than one might 

 at first imagine ; both have perennial creeping root-stocks 

 as reserves of material ; but that of the stone-bramble 

 only sends up green annual shoots, herbaceous in character ; 

 while that of the raspberry sends up rather stouter and 

 woodier biennial stems, which seldom outlive the second 

 year. In the blackberry, they sometimes continue for three 

 or four years together. Such gradual intermediate stages are 

 almost universal in nature. At the same time that the higher 

 brambles have acquired their woody and creeping habits, 

 they have also acquired sharp prickles, rather weak in the 

 raspberry, stout and usually hooked in the blackberry. 

 These prickles not only serve to defend the plants against 

 the cattle that browse (or the deer that once browsed) 

 among the thickets where they love to grow, but also aid 

 them in clambering over the bushes, hedges, or heaps of 

 stones over whose top they usually straggle. The 

 raspberry flowers are white ; but the blackberry often 

 shows a tinge of pink in its much larger petals which 

 reminds us of such bigger and more developed rose-flowers 

 as apple blossom, cherry blossom, and the true roses. 

 Side by side with these changes, the leaves, now growing 

 out into the open by the aid of the woody stems, can afford 

 to expand more freely and widely ; and so, instead of the 

 simple lobed leaf of the cloudberry, or the trefoil leaf of 

 the stone-bramble, these higher types have usually leaves 

 of five leaflets, though the gradation from the three-leaved 

 to the five-leaved form can almost always be observed upon 

 the same plant. In the wild raspberry, as everybody knows, 

 the fruit is still red, like that of most other brambles, but 

 the blackberry seems to suit our native birds better, with 

 its dark purplish-blue tinge, than any of these brilliant 

 northern kinds. Indeed, it is noticeable that very dark-blue 

 and black, which are extremely rare colours in flowers, are 

 extremely common in wild fruits — for example in sloes, privet, 

 whortleberries, wild madder, elderberries, dogwood, and 

 wayfaring-trees. This seems to suggest a diflerence of 

 taste in colour between birds and insects. The true 

 blackberry has no bloom on the fruit, but in the variety 

 known as the dewberry, and commonly accounted a species, 

 the berry is covered with a delicate blue-black mealiness which 

 makes it a very pretty object indeed. Blackberry brambles 

 in fact, show an immense tendency towards variation — so 

 much so, that while Mr. Bentham makes two British 

 species, and Sir W. Hooker six. Professor Babington 

 actually distinguishes as many as forty. As yet, however, 

 it does not seem to me that any special selective action has 

 been exerted upon these numerous varying forms, and, 

 therefore, from the evolutionary point of view, they must 

 te regarded as mere accidental sports, not as true botanical 

 species. 



THE CHEMISTRY OF COOKERY. 



By W. Mattied Williams. 

 XIX. 



REFERRING to No. 17 of this series, August 1, a 

 correspondent who has just returned from Norway, 

 where he followed the route of my last trip there, reminds 

 me of the marvellous congregation of sea-birds that 

 assembles on some of the headlands of the Arctic Ocean, 

 and suggests that egg-oil might be obtained in large quan- 

 tities there. He quotes from the work of P. L. Sim- 

 monds on " Waste Products " the following : — " In the 

 Exhibition of 1862 the Russian Commission showed egg- 

 oil in large quantities and of various qualities, the best so 

 fine as to far excel olive oil for cooking purposes ; " but it 

 was not sufficiently cheap for general use. 



Among the places indicated by Mr. Grimwood Taylor, 

 the most remarkable is Sverholt Klubben, a grand head- 

 land between the North Cape and Nord Kyn, rising pre- 

 cipitously from the sea to a height of above 1,000 feet. 

 The face of the rock weathers perpendicularly, forming a 

 number of ledges about two or three feet above each other, 

 and extending laterally for more than a mile. On the two 

 occasions when I passed it, the whole of this amphitheatre 

 was occupied by a species of gull, the " kittiwake," perched 

 on the ledges, their white breasts showing like the shirt- 

 fronts of an audience of a million or two of male pigmies 

 in evening dress. On blowing the steam-whistle, the rock 

 appeared to advance, and presently the sky was darkened 

 by a living cloud, and every other sound was extinguished 

 by a roar of wings and the harsh wailing screams of a 

 number of birds that I dare not estimate. The celebrated 

 bird colony on the Bass Rock is but a covey compared with 

 this. 



The inhabitants of the little human settlement in the 

 Bay of S\erholt derive much of their subsistence from the 

 eggs of these birds ; but wliether they could gather a few 

 millions for oil-making without repeating the story of the 

 goose and the golden eggs, is questionable. The eider- 

 ducks that inhabit some of the low mossy islands there- 

 abouts, are guarded by strict legislative regulations during 

 their incubation period, lest they should emigrate, and the 

 down-harvest be sacrificed. 



I now come to the subject of stewing, more e.speciaUy 

 the stewing of flesh food. Some of my readers may think 

 that I ought to have treated this in connection with the 

 boiling of meat, as boiling and stewing are commonly 

 regarded as mere modifications of the same process. 

 According to my mode of regarding the subject, i.e., 

 with reference to the object to be attained, these are 

 opposite processes. 



The object in the so-called "boiling" of, say, a leg of 

 mutton is to raise the temperature of the meat throughout 

 just up to the cooking temperature (see Nos. 3 and 4) in 

 such a manner that it shall as nearly as possible retain all 

 its juices ; the hot water merely operating as a vehicle or 

 medium for conveying the heat. 



In stewing nearly all this is reversed. The juices are to 

 be extracted more or less completely, and the water is 

 required to act as a solvent as well as a heat-conveyor. 

 Instead of the meat itself surrounding and enveloping the 

 juices as it should when boiled, roasted, grilled, or fried, 

 we demand in a stew that the juices shall surround or 

 envelope the meat. In some cases the separation of the 

 juices is the sole object, as in the preparation of certain 

 soups and gravies, of which " beef-tea " may be taken as 

 a typical example. Extractum Carnis, or " Liebig's 



