POPULAR MISCELLANY. 



713 



of inoculating a rabbit with the blood was 

 negative (as in the great majority of pre- 

 vious cases of inoculation with blood of ani- 

 mals under rabies). But with the saliva it 

 was different. A rabbit inoculated in the 

 ear and abdomen on the 11th of October 

 began to show symptoms of rabies on the 

 15th, being much excited and damaging the 

 walls of its cage, while it uttered loud cries 

 and slavered at the mouth. Then it fell 

 iuto collapse and died the following night. 

 The rabbit's body was dissected thirty-six. 

 hours after death, and further experiment 

 was made by taking fragments of the right 

 and left submaxillary glands and introduc- 

 ing them under the skin of two other rab- 

 bits respectively. These two rapidly suc- 

 cumbed, one on the fifth, the other on the 

 sixth day (becoming visibly ill on the third) ; 

 neither passed through a fui'ious stage, 

 however, and the predominant feature was 

 paralysis. The important practical result 

 is, that human saliva, such as caused rabies 

 in the rabbit, is necessarily virulent, and 

 would probably have corresponding effects 

 on man; so that it should be dealt with 

 cautiously, and that not only during the life 

 of the person furnishing it, but in post-mor- 

 tem examinations. 



The Agency of Plants in Earth-Bnilding. 



— The important question of the part taken 

 by plants in earth-building is discussed by 

 Professor Ernst Hallier, of Jena, in a popu- 

 lar essay on " Plants and Man in their In- 

 terrelations." The contributions made by 

 the vegetable world to the formation of 

 the crust of the earth are most obviously 

 shown in the beds of peat and coal, the 

 remains of former immense forests and 

 swamps. These formations, remarkable 

 and important as they are, Professor Hal- 

 lier observes, are far exceeded by the less 

 apparent changes which are effected by the 

 agency of plants. The deposits of fresh- 

 water limestones are largely the results of 

 plant-action. Nearly all the streams in cal- 

 careous regions bring down carbonate of 

 lime in solution as a bicarbonate. Their 

 waters being charged with carbonic acid or 

 having absorbed it from the air, are by its 

 aid enabled to act upon the otherwise insol- 

 uble carbonate of lime, and to take up a 

 quantity of it proportioned to the amount of 



carbonic acid they contain. This dissolved 

 lime is in its turn converted by the plants 

 which grow in and under the water into 

 stone. All the carbon that is needed for 

 the organic world, arumals as well as plants, 

 is obtained through the action of plants 

 in extracting carbonic acid from the air. 

 Plants and those parts of plants which are 

 under water do not stand in direct relations 

 with atmospheric air, but are dependent on 

 the carbonic acid which is held in the water, 

 and, when this is exhausted, on the dissolved 

 bicarbonate of lime. A part of the car- 

 bonic acid is taken up from this substance 

 by the chlorophyl-cells, while the other 

 part remains fixed in the lime in the form 

 of simple carbonate of lime. Since the lat- 

 ter is insoluble in water, it is deposited just 

 where it happens to be, which in this case 

 is on the surface of the plant, and this be- 

 comes covered with a coating of limestone. 

 Fresh supplies of water bring down new 

 stores of carbonic acid and the dissolved 

 bicarbonate of lime, and the plants continue 

 their work of converting the latter into the 

 insoluble carbonate. Thus the work goes 

 on unceasingly, and crust on crust of lune- 

 stone is deposited on millions of small 

 plants. The plants themselves die, wholly 

 incased in stone, but new ones succeed 

 them, and the layers of petrified plants bear 

 in continuous succession a green coating of 

 growing plants. Strata are added to strata, 

 and the limestones grow enormously through 

 the quiet activity of the charae, mosses, 

 reeds, grasses, and other plants in the water. 

 Fresh-water limestones are thus still in pro- 

 cess of formation in all limestone regions. 

 The minor valleys of the Thuringian Valley 

 contain large bodies of soft, fresh-water 

 limestones, in which the forms of the plants 

 to whose action they are due may be plain- 

 ly recognized, partly in incrustations, part- 

 ly in impressions, mixed with fresh-water 

 shells and with remains of the trees which 

 once grew on the shore. The material, 

 though soft, has been used in the manufac- 

 ture of a building-stone out of which cities 

 like Jena and many towns have been built. 

 Rock-building of this kind has been going 

 on ever since there was a growth of plants 

 on the earth, and has during that time 

 played a considerable part in forming the 

 crust of the earth. Other far smaller plants 



