506 



SCIENTIFIC NEWS. 



[Nov. 1 6, 1885; 



with their leaflets naturally conduplicate or otherwise 

 protected as in nature. In the morning I weighed each 

 group again, and reduced their losses to percentages of 

 the original weights of each group respectively. I 

 found that there was in every case a generally much 

 greater loss in the case of the leaves artificially exposed 

 than with the others, as will be seen from the following 

 examples : — 



Loss p. c. Loss p. c. 



Laurustinus, exposed naturally 87. Spread out, 187 



Portugal Laurel „ ,, 8"4 ,, ,, 126 



Lime „ , 4-5 „ „ 21-4 



Laburnum „ „ 14-8 „ „ 330 



Ash „ „ 23 „ „ II-8 



Rose „ ,, 106 „ „ I7"6 



Periwinkle ,, „ 50 ,, ,, 1205 



Clover „ „ 244 „ „ 293 



Walnut „ ,, 187 „ „ 24-6 



Very few nights of the month (May, 1885) were frosty, 

 so that several attempts to carry out experimenls were 

 unsatisfactory, as so many nights were cloudy, windy, 

 and stormy, and ill-suited for radiation ; yet on one 

 occasion, when about three degrees of frost occurred, the 

 Walnut, Lime, and Laburnum leaves when spread out 

 showed to the eye unmistakable injury ; whereas these 

 three kinds of leaves, placed as they occur on the trees, 

 did not appear to be hurt. Other leaves treated in the 

 same way and subjected to the same slight frost did not 

 appear to have suffered ; but I had not at that time 

 thought of weighing them. 



I will now add a selected series to illustrate the various 

 methods adopted whereby the young and developing 

 leaves are protected from injury by radiation. 



I. Simple Leaves, (i) Opposite : (i) erect. — This position 

 is assumed in all cases of opposite leaves which I have 

 had an opportunity of examining. The leaves face one 

 another with their upper surfaces more or less in close 

 contact, concealing the bud between them. In shrubby 

 Veronicas and Hypericums and Periwinkle the leaves are 

 almost, as it were, glued together, so firmly do they 

 cohere all round the margins. In others, such as Aucuba 

 and Laurustinus, they are more slightly adjusted. The 

 only exceptions that I have met with were Snowberry, 

 Weigela, Honeysuckle, and the leaflets of the Elder, all 

 being of the same family, Caprifoliacese.* The pairs 

 of leaves had their edges involute, and one of each pair 

 slightly embraced the opposite leaf, and so wrapped up 

 the bud within it. 



(ii.) pendulous. I have not met with any instance of 

 opposite leaves being pendulous in the young state. 



(2) Alternate : (i.) erect. — Good examples may be seen 

 in the Common and Portugal Laurels (fig. 1). As the upper 

 surfaces of different leaves cannot be in contact, issuing 

 from separate nodes and at different elevations, each leaf 

 is conduplicate, i.e, the two halves of the blade are folded 

 together and thereby press their upper surfaces of the 

 halves against one another; indeed, so tightly is this 

 done, that it is not at all easy, in many instances, to sepa- 

 rate them. It may be noted here that the conduplicate 

 vernation is an extremely common one both for simple 

 and compound leaves, and the significance of it will be 

 now very apparent. It is sometimes further complicated 

 by having the surfaces plicate, as in the Vine, Beech, 

 Maple, Currant, Raspberry, etc., conditions which are 

 probably additional safeguards against radiation. 



* I first discovered this difference in Weigela, and that led me to 

 examine the others, which revealed the fact that this peculiar form 

 of vernation is an ordinal character. 



As other instances of the erect position may be- 

 mentioned Rhododendron, the leaves of which, as of the 

 Dock and Primrose, are revolute ; but those of the Violet, 

 Pear, and Michaelmas Daisy are also erect but involute, 

 while the Cherry has them convolute. In all these the 

 undeveloped leaf is cylindrical or an elongated cone, 

 erect, and offers no extent of surface, while the margins, 

 the most sensitive parts, are specially protected. 



(ii.) pendulous. The Lime, Hazel, and Ampelopsis 

 Veitchii are good examples. In the case of the Lime, as 

 soon as the bud expands and escapes from the winter 

 (stipular) scales, the inner stipules develop considerably : 

 those on the upper side are concave and ovoid and cover 

 the upturned edges of the conduplicate leaves, which at 

 once take a position in a vertical plane ; the stipules at 

 the sides elongate much more than the former, furnishing 

 some lateral protection to the whole bud, which now 

 curves strongly downwards, and somewhat resembles a 

 mussel in shape (fig. 2). As the bud continues to develop, 

 the branch becomes more and more strongly curved 

 downwards, so that the leaves are held vertically (figs. 3 

 and 4) ; and as the lower and older ones increase in size, 

 they assume a horizontal position and undertake to 

 protect the younger ones, which are concealed beneath 

 them. Thus the protecting care is handed on to each leaf 

 as it arrives at maturity, until the whole series are 

 developed and the branch and leaves become horizontal. 

 (To be continued.) 



WATER AS A CONSTITUENT OF 

 ORGANIC SUBSTANCES. 



WATER, says Dr. Whitelaw, forms three-fourths of 

 the weight of living animals and plants, and 

 covers about three-fourths of the earth's surface. Pro- 

 fessor Chaussier dried the body of a man in an oven, like 

 a brick in a kiln, and after desiccation the body weighed 

 only twelve pounds. Rather more than a pound of water 

 is exhaled daily by the breath, about r| lbs. by the skin, 

 and 2| lbs. by the kidneys, making the daily emissions of 

 water by the body about 5! lbs., or not quite three 

 quarts. The following is the percentage of water in 

 some well-known articles : — 



Wheat 



... is 



Mangel vvurzel 



... 85 



Barley 



... is 



Cabbage (leaves) ... 



... 9? 



Oats 



... 16 



Cabbage (stem) 



... 84 



Rye 



... 12 



Mushroom ... 



... 96 



Rice 



... 13 



Fungi 



86 to 95 



Beans (field) 



... is 



Potato 



... 75 



Beans (kidney) 



... 23 



Water melon 



... 94 



Peas 



... 14 



Cucumber ... 



... 96 



Turnips 



... 88 



Vinegar plant 



... 9S 



Carrots 



... 83 



Wheat flour 



13 to 16 



Rye flour ... 



... 14 



Cocoa 



••• 5 



Barley flour 



... 14 



Manna 



... 10 



Indian corn flour .. 



.... 14 



Figs 



... 21 



Oatmeal 



... 14 



Plums 



... 75 



Wheat bread 



44 to 48 



Apples 



... So 



Rye bread ... 



44 to 49 



Gooseberries 



... 80 



Cane sugar 



••• 5 



Peaches 



... 75 



Linseed cake 



... 10 



Egg (entire) 



... 74 



Flesh 



.... 77 



Milk 



... 87 



Skin 



... 58 



Blood 



79 to 83 



Bones (variable) ... 



7 to 20 



Gastric juice 



... 97 



Beef ' 



... 74 



Trout 



... So 



Veal 



... 75 



Pigeon ... „ 



... 79 



Mutton 



... 71 



Cheese 



... 40 



Haddock 



... 82 



Brandy 



... 56 



Sole 



... 79 



Whisky 



... 47 



Tea 



... 5 



Rum 



... 30. 



Coffee 



... 12 



Beer 



... 9a 



