WILD LIFE IN CALIFORNIA 



85 



secretes a digestive fluid which is said to be 

 similar to the digestive fluids of animal life 

 in its chemical composition, and the leaves re- 

 main closed until the softer parts of the victim 

 are digested, or in short plain words, eaten by 

 the plant. There are four or five other in- 

 sect-killing plants of different forms, one 

 growing in our Sierras, possessing the habit 

 of capturing, killing and devouring flies and 

 other insects. Other somewhat remarkable 

 exceptions are the enlarged and thickened 

 leaves of the agave and certain members of 

 called leaves is the storage of nourishment 

 and water that, not unfrequently, have been 

 the means of saving the lives of men and 

 beasts who, through some misfortune or mis- 

 calculation, were without food and drink. 



The botanists say the tendrils of climbing 

 plants, the sharp thorns, like those on the 

 honey-locust tree, and the concentric layers 

 of the onion and tulip bulb are but leaves 

 in a modified form. In the case of tulips and 

 similar bulbs, the special service of the so- 

 called leaves is the storage of nourishment 

 elaborated by the leaves above ground for the 

 growth in the following year of the plant and 

 flower and production of new bulbs. In doing 

 this the old bulb is almost entirely absorbed. 

 The bulb found in its place is wholly a new 

 one. If the soil and climatic conditions are 

 favorable several new bulbs will be produced. 



The small leaves that form over the buds 

 of branches for their protection in the winter 

 are called bud-scales. In some cases after 

 fulfilling that duty they fall off when the 

 blossom or foliage develops. The bud-scale 

 of the lilac, however, after the protecting 

 service is ended, becomes an ordinary leaf, 

 and with the dogwood it eventually becomes 

 a showy part of the flower. 



Leaves have the power of movement, but 

 it is rather insignificant except in compara- 

 tively few species. Nearly all kinds can and 

 will return to their natural position when 

 twisted round so as to be upside down, if not 

 too rudely done. The most common move- 

 ment is among plants the leaves of which 

 change their position at evening for the night 

 and resume a daylight position in the morn- 

 ing. Then there are some plants known as 

 sensitive plants, for the reason that when 

 lightly struck, or jarred, the small leaflets 

 suddenly close and fold up along the stem. 

 But the most remarkable instance of inde- 

 pendent movement is described as occurring 

 with a plant growing in some parts of India, 

 commonly styled the Telegraph plant. Each 

 leaf stem, or petiole, bears three leaves; the 

 middle, or terminal leaf is somewhat of the 

 shape of a small leaf of a peach tree. This 

 droops at night and rises with the beginning 

 of the day. The other two leaves, which are 

 very much smaller, under certain conditions 

 of temperature keep up an incessant move- 

 ment not unlike the flopping ears of a fly- 

 bothered animal. 



Whatever peculiarity of shape and size 

 leaves may have, power of movement they 

 possess, or special service in supplying forage, 

 shade, or storing nourishment for future gen- 

 erations of its own kind, the principal and or- 



dinary purpose of leaves, in conjunction with 

 the roots, is that of maintaining the exist- 

 ence and growth of the plant to which they 

 belong; and in this function they exhibit the in- 

 tricacies of a machine shop and the wonders 

 of a chemical laboratory. But before we enter 

 into the details of this relation it is necessary 

 that we should review the principal features 

 in the growth of plant life to secure a better 

 and clearer understanding of the subject. 



Growth of a plant signifies increase of its 

 substance and its size generally involving some 

 change in form. All the details of what takes 

 place are not fully known, although the main 

 principles involved have been pretty well es- 

 tablished by scientists. They tell us that the 

 active element of all life is protoplasm, a fluid 

 form, and all manner of growth depends upon 

 the multiplication or increase in number of 

 the cells possessing this vital force. Through 

 the agency of the nucleus, which each cell 

 contains, the protoplasm multiplies itself by 

 division of the cell contents into two parts, 

 each of which, upon maturing, continues the 

 process of division. The multiplication of the 

 cells represents an increase of substance or 

 what we call growth. 



The walls of the cells are of a different 

 material which in the tree and shrubs are 

 elongated and become what we call wood. 

 The walls gradually grow thicker and stiffer. 

 The harder the wood, the thicker and more 

 dense the cell walls. There are other cells 

 and ducts for the passage of the tree saps 

 which also increase in number in keeping with 

 the increase of the cells of protoplasm. These 

 also represent an increase of substance. So it 

 is apparent that the tree or shrub in addition 

 to protoplasm elaborates another growing 

 agency, for the cell walls are mainly com- 

 posed of what is called cellulose, a different 

 combination of the chemical elements, that 

 becomes the principal part of the structure of 

 every tree. 



For the formation of these growing forces 

 the tree or plant absorbs from the soil and 

 from the air and water certain chemicals 

 heretofore enumerated. The chemicals are in 

 gaseous and soluble form and usually are 

 assimilated in quantities in excess of immedi- 

 ate needs and these excesses go to form sugar, 

 tannin, resin, and many other commodities, 

 according to the species. Excesses are also 

 stored away in different parts of some plants 

 in soluble forms of sugar, or as dextrine, or as 

 starch, for use as seasonal or other conditions 

 may demand. A part is stored in nuts and 

 seeds and is used in providing a supply of 

 nourishment for the young seedlings for the 

 first few days of their existence. In some 

 vegetable growths, as in the sugar maple tree, 

 sugar cane and sugar beets, the excess stored 

 is appropriated by man and becomes the 

 sugars of commerce. 



In the history of the operation of the life 

 forces or growth of a tree, say an almond tree, 

 the beginning is the seed, the common almond 

 of which the lovers of nuts are so fond. The 

 germ of life with its dormant protoplasm and 

 nucleus lies in the little bud-like form between 

 the two meaty, parts of the nut that we eat. 



