LESSONS IN BOTANY.

which is wrapped about the seed much more closely. On
one side of the grain a groove
Fig. 5.
may be observed; and at the
base on the opposite side, a
small oval lump, which shows
the germ of the future plant.
The vessels by which the
grain was attached to the
plant, and through which it
drew support until its ma-
turity, were at the lowest end
of this protuberance. When
the seed is perfectly ripe,
these vessels separate, the
point of separation speedily
heals, the grain may then be
easily threshed out from the
chaff in which it had been
buried, and sometimes it sheds
itself spontaneously.

Wheat is very widely dif-
fused. It flourishes not only
in our temperate clime, but
also in the extremes of heat
and cold. In Lapland it is
cultivated as far as sixty-
eight or seventy degrees north
latitude; and Humboldt
found, in the neighbourhood
of La Victoria, at the height
of more than 2,000 feet above
the ocean, some fields of
wheat, mingled with planta-
tions of coffee, plantains, and
sugar-canes. Thus, as it is
the plant most necessary to
mankind, so it is the most
general; while its presence
in any region of the earth,
attests the civilisation of man.
In the sepulchres of the Egyptian kings, for example, the
common wheat was found in vessels so perfectly closed, that
the grains retained their form and colour; and as the corn-
plants do not grow wild in any part of the earth, and appear
Fig. 6.

Barley is grown to almost as great an extent as wheat; more
particularly in the East, as in Egypt and Syria, where it forms
the staple grain for making bread. It wants, indeed, the sub-
stance called gluten, which appears peculiar to wheat, and makes
flower form so good a paste, and which is essential in render-
ing fermented bread light. But in the East, barley is chiefly
used for unleavened bread, in the form of thin cakes, so com-
Pearl barley is the same vegetable,
mon among the peasantry of Scotland, and not unpalatable to
those accustomed to its use.
only freed from the husk by a mill. Barley-water, a decoction
of pearl barley, is a valuable beverage. In the engraving, fig.
6, A represents the common kind, and в the fan barley.

The seeds of a corn plant are sometimes placed on a single rib or rachis, as in wheat and barley, and they then form a spike. In what is called Egyptian wheat this spike is compound, there being more than one rib, and if this consists of branches that are naked at their points of junction, and have spikelets at their extremities, they form a panicle; such, for example, is the case with oats. Oats will grow in soils which will not bear wheat or barley, and in situations not adapted to other grain. In the mountainous parts of Scotland, and the hilly districts of Derbyshire, it is almost the only grain cultivated. The ear of the oats blade has two forms, which are represented in the engraving, fig. 7. While young and light.

Bailey.

as they do under culture, they show as clearly the civilisa-
tion of that country, as its temples which are now in ruins.

the branches arrange themselves round the centre of the stem; but as they advance towards maturity, and acquire weight, they generally bend over on one side. Thus, a beautiful provision is made for the health of the plant. For now the air and light can visit it freely, and the rain may wash every individual grain, and preserve it from the seeds of any destructive plants. And then, as the grains are pendent and have the open extremities of the chaff towards the earth, they are effectually defended from the lodgment of rain within-an advantage which neither wheat nor barley possesses, and hence are liable to diseases from which oats are exempted.

Such, then, is a brief description of some of the cultivated grasses, which have become so familiar, and so valuable as corn; and we may conclude the present lesson with an interesting and instructive anecdote related by Pliny. Cresinus, a Roman, was cited before an assembly of his people, on a charge of sorcery, from his reaping much larger crops than others from a small piece of ground. In answer to the charge, Cresinus produced his implements of husbandry, his well-fed oxen, and a hale young woman, his daughter, and pointing to witchcraft; but I cannot here show you my labours, sweats, them, he exclaimed, "These, Romans, are my instruments of

and anxious cares." And so it is in many other instances. 2. Find the products of the number 98998, by all the numbers We see the result, it may be with pleasure or astonishment, from 11 to 49 inclusive, and the answers will be found in the table but the skill-the toil that secured it, is hidden from our view. given in Exercise 6, page 58, No. IV. Let us remember, however, that nothing valuable is gained 3. 70508 × 70508; without effort, and that labour, wisely directed and persever-14-857142857×7777. ingly employed, will achieve what many would regard as absolutely impossible.

9 18 27 36 45 54
36 45 54 63 72 81 90 99 108 117 126 135 144 153 162 171 180

19 19 38 57 76 95 114 133 152 171 190 209 228 247 266 285 304 323 342 361 | 380 | 20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400

take the vertical column of the products of 14, then the number of stones (weight) answering to any number of pounds in this column, will be found in the first vertical column on the left hand. Thus, if you wish to know how many stones are in 238 pounds, look down the column having 14 at the top for the number 238, and in the same horizontal line with it, on the left, in the first vertical column stands 17, the number of stones.

DEFINITION.-When a number is multiplied by itself, the product is called the square of the number. Thus, when we say 9 times 9 are 81, the number 81 is called the square of 9. The name square is borrowed from applied geometry, because in finding the area of a square, the length of whose side is given, we multiply this length, given in numbers, by itself, and the product is the area. Thus, if the side of a square was 6 feet long, the area of the square would be 36 square feet; because 6X6 = 36.

The table given above contains, diagonally (that is from corner to corner) from the blank corner to 400, in the last square on the right, the squares of all the numbers from 1 to 20. The square of any number is found at the place where the vertical and horizontal columns, that contain the number, meet. Thus, the square of 12 is found by running the eye down the column having 12 at the top, till it come to the horizontal column having 12 at the beginning. The square of 12 is thus found in the table to be 144.

LESSONS IN PHYSIOLOGY.-No. IV.

MAN.

|

We take, for granted, that you now understand the theory of THE CIRCULATION OF THE BLOOD. Plants have no blood, but they have a circulation. In the leaf, the ascending sap undergoes such an elaboration or preparation as adapts it to the nourishment and growth of the plant; and from the leaf, there is a network of small vessels, which runs along the branches of the stem and roots, and by which the sap is thus conveyed to every part, till it is all but entirely exhausted by the different tissues through which it has circulated, taking up into themselves all its nutritive matter. The only condition necessary for the life and increase of the lowest plants, is, that they be in immediate contact with the two elements of air and water. Their whole substance is nourished by means of the fluid which surrounds them. Take, for example, the SEAWEEL-every part of its soft external surface being equally in contact with the water, every part of the weed takes from the surrounding fluid, and assimilates whatever is suited to itself. It is only, as we ascend the scale of animal life, that we find provision made for circulation; and this provision may consist of a single vessel, with the power of contracting and sending forward the fluid which it contains through all the vessels that issue from it, as in the STAR-FISH, up to the complex and wonderful structure and apparatus of the human heart.

In a chemical point of view, the blood represents the whole body in a liquid state, since the blood contains all the elements which enter into the human frame, and which are combined in the form of albumen, febrine, colouring matter, fat, and salts. It is owing to this composition that the blood is fitted to furnish the materials of growth and increase to every individual part. But while it furnishes the materials of nutrition to every part of the body, it sustains itself a positive loss; and this loss must be continually made up, otherwise the blood will no longer be fitted to minister to the nutrition of a single part. If every tissue in the body is taking from the blood that which is adapted to support and preserve itself, then we must restore to the blood that which it has lost. This we do by the food which we eat, and the air which we breathe.

If the loss which the blood sustains is to be made up by our taking food, then the food itself must undergo certain changes. The first change takes place in the mouth. Why has the great Creator furnished the mouth with two rows of teeth? Though essential to beauty, they were given not for ornament only, but for use. Most articles of food require to be masticated or chewed. And for this a beautiful provision has been made in the teeth, of which we have sixteen in each jaw. Four of these are placed in the front, and are called INCISORS, from their power of cutting or dividing the food; two are named CANINE or dog. like teeth; and the other ten are known as molars or grinders.

II/IVOVO

In the act of chewing, the food becomes mixed with the SALIVA of the mouth, which partakes of an alkaline, and so reduces it into a kind of pulp. Till it is so reduced, it is not in a fit state to pass into the stomach. In the stomach the gastric juice should have access to every particle of matter that passes into it; but this is impossible unless there be a thorough admixture of the food and the saliva in the mouth. Persons who eat fast never sufficiently chew their food; being imperfectly chewed it never becomes thoroughly mixed with the saliva: and passing into the stomach in this state, it never digests as it ought, and hence such persons are doomed to suffer all the horrors which arise from indigestion. The mouth into which the food is received is lined with a beautiful thin membrane or covering, which extends backwards, and terminates in a common tube or funnel, which is called the PHARYNX. The pharynx is divided into prolonged tubes, one of which descending from the pharynx is called the ESOPHAGUS, or commencement of the digestive canal; while the other, which is situated in the pharynx and named the LARYNX AND TRACHEA, is the passage to the lungs or respiratory organs The digestive canal traverses the chest, developes itself in the bowels, terminates in the anus, and in its whole course represents a tube whose superior opening is the mouth.

Although the quantity of saliva formed in the mouth during four-and-twenty hours is from fifteen to twenty ounces, yet its flow takes place only as it is wanted, or as food is taken into the mouth, and the work of mastication goes on. But if you are hungry, and pass the kitchen during the process of cooking, or go into a room in which a nice dinner is being served, or even let your mind be directed to some favourite dish, there will be an instant flow of saliva, or to use the common phrase -a watering of the mouth.

The human body is made up of an assemblage of countless cells; but the arrangement and disposition of these cells is such, that they cannot all come into immediate contact with the influences of the external world, as in the case of a simple plant. Between the external world, however, and these cells, there comes the nutritive and vital fluid of the blood, which goes to every individual part of the body, and which, in its circulation, represents two distinct currents. One current conveys to the cells the material of nutrition and secretion; and the other current carries away from these cells the materials of absorption. The vessels or tubes, in which these currents are performed, are called the arteries and the veins. The arteries convey the blood in its pure and vital condition to every part of the system, and the veins take it up in a degenerated state, and carry it back to the heart and lungs, to come in contact with the air in the organs of respiration; while the The food being prepared by the mouth, this is followed by absorbents are small, delicate, transparent vessels, which take the act of swallowing. The pulp passes from the mouth into up from the surface of the body, or from any cavity, those por- the œsophagus, which descends from the pharynx into the stotions of nutritive matter which are not in a state of perfect mach. The stomach, of which the annexed engraving is but solution, and which, by passing through the thoracic duct, a simple and imperfect representation, is the grand receptacle or the passage which lies in the front of the spine, between the for the food, and in which it comes into immediate contact chest and the belly, is prepared for entering into the current with the GASTRIC JUICE. While the saliva is alkaline, this of the blood. These little vessels are called LACTEALS, from juice is acid, and is poured forth from the walls of the stomach the Latin word LAC, which signifies milk, because of the milk-on every successive introduction of food. The presence of food like appearance of the fluid; or LYMPHATICS, because they is necessary to excite this fluid, and hence it is never detected absorb the lymph or superfluous moisture which is found in the in the empty stomach. Its flow may be increased by taking a body. small quantity of salt, pepper, mustard, or any other stimu

LESSONS IN PHYSIOLOGY.

liquids-the bile and the pancreatic juice. The PANCREAS is a
flat roundish gland, in form like the tongue of a dog, situated
its appearance and chemical properties, and whose use seems
to be to dilute the chyme, and to incorporate it with the bile, so
behind the stomach, and secretes a liquid resembling saliva in
as to produce the chemical changes necessary for the formation
of CHYLE. The secretion of bile, is, therefore, a process of the
highest importance in the human economy. Of this we feel
sure from the size of the liver, and the large supply of blood
which it receives. Though we are comparatively ignorant of
the chemical action of the bile upon the chyme, it cannot be
denied that the bile itself serves the most useful and beneficial
purposes in the process of digestion. Among these uses, we
may name the following:-

It renders more soluble the fatty matter that enters into most of our food.

It takes from the chyme a certain portion of its acidity, if its acid be in the extreme.