This name is given in botany to the summit or top of the stamen containing the fertilizing fruit-producing dust. Pollen is the fecundating dust or fine substance, like flour, meal, or fine bran. Farina, contained in the anther of flowers and plants, which is dispersed on their stigma for impregnation, form a vegetable essence constituting the particular nature of a substance forming the flower existing in other plants of the same family or kind. Spore or sporule in botany is that product of flowerless plants which performs the function of seeds. These substances float in the atmosphere, and are the cause of the hay fever; and when they fall into water and are afterwards left upon mud they ferment, and being dried up by the sun they fly about with the spawn of animals. Should seeds fly about with the pollen or farina in a state of decay and full of carbonic acid, the oxygen of the atmosphere, so essential to human beings, is diminished, and the pollen or seeds are inhaled into the lungs, and are thus exposed to the action of oxygen whilst circulating with the blood. The result of an excess of carbon in the air is the growth of ferns on barren rocks, which ferns subsequently become coal. The same cause will always produce the same results. When vegetable matters rise from a large surface of earth or mud (as from the newly-drained forty thousand acres of the lake of Haarlem), there are no plants there to inhale the carbonic acid, and to give out oxygen; but those seeds being rotten or in a state of ferment, the oxygen for the decomposition is drawn from the atmosphere alone, and human beings who breathe this malaria have fever; the atmosphere is tainted: miasms of carbon with hydrogen gas (the lightest thing known) fly about, carrying them to points where sulphurous gases may find them a resting-place on mud and shallow waters: these give rise to fever, cholera, plague, and to all zymotic diseases. NOTE 5.--_Algæ, or Sea-weeds of the Mediterranean Sea._