150 INDEHISCENT FRUITS. the name diachanium has been given to this fruit. Examples of the cremocarp as above defined are found universally in the order Umbelliferæ, but in no other order. 2. The Cypsela.-This differs from the achenium only in being inferior and of a compound nature. It occurs in all plants of the order Compositæ. 3. The Glans or Nut is an inferior, dry, hard, indehiscent, one-celled, one- or two-seeded fruit, produced from an ovary of two or more cells, with one or more ovules in each cell, all of which become abortive in the progress of growth except one or two. The three layers constituting the pericarp of the nut are firmly coherent and undistinguishable, and the whole is more or less inclosed by a cupule. The Acorn and the Hazel-nut may be taken as examples. b. With a Fleshy, Indehiscent Pericarp.-1. The Bacca or Berry is an inferior, indehiscent, one or more celled, many-seeded, pulpy fruit. The pulp is produced from the placentas, which are parietal, and have the seeds at first attached to them; but they separate later and lie loose in the pulp. Examples may be found in the Gooseberry and Currant. The fruit of the Grape differs in nothing essential from the berry, except in being superior. The name baccate or berried is applied by many botanists to any fruit of a pulpy nature. 2. The Pepo is an inferior, one-celled, or spuriously three-celled, many-seeded, fleshy or pulpy fruit. The seeds are attached to parietal placentas, and are imbedded in pulp, but they never become loose as is the case in the berry; and hence this fruit is readily distinguished from it. 3. The Pome is an inferior, indehiscent, two or more celled, few-seeded, fleshy fruit; the endocarp of which is papery, cartilaginous, or bony, and surrounded by a fleshy mass consisting of mesocarp and epicarp, which is generally considered to be formed by the cohesion of the general parenchyma of the ovary with the tube of the calyx. Some botanists, however, regard the fleshy portion as consisting of the enlarged end of the flower-stalk, in which the true carpels are imbedded. Examples may be seen in the Apple, Quince, and Medlar. II. Fruits formed by the Combination of Several Flowers.-These fruits have been termed Anthocarpous, as they consist not only of the mature carpels or ovaries of several flowers united, but also usually of the bracts and floral envelopes in combination with them— that is to say, the whole inflorescence is blended to form a fruit. They have been also called Multiple, Collective, and Infrutescences or Confluent Fruits. Such fruits have been likewise termed polythalamic, to distinguish them from fruits formed from single flowers, which are called monothalamic. The following may be mentioned: I. The Cone is a more or less elongated fruit, composed of a number of indurated scales, each of which · bears one or more naked seeds. It is the fruit of a great many plants of the order Coniferæ, which derives its name from this circumstance. Some botanists regard the scales as carpels spread open, others as bracts. They certainly more resemble the latter organs in appearance, as they never present any trace of style or stigma on their surface. Some, again, regard the cone as the spurious fruit (page 136) or pseudocarp of a single flower, and not as a collection of fruits, as here described. 2. The Galbulus.-This fruit is a modification of the Cone, being more or less rounded in form instead of conical, with the heads of the scales much enlarged. In the Juniper the scales become fleshy, and are united together into one mass, so that it somewhat resembles at first sight a berry, but its nature is at once seen by examining the apex, when three radiating lines will be observed corresponding to the three scales of which the fruit has been formed, and which are here but imperfectly united. No other kind of fruits except the Cone and Galbulus 152 COLLECTIVE FRUITS. are found in the natural orders Coniferæ and Cycadaceæ, the so-called fruit of the Yew being simply a naked seed surrounded, except at the apex, by a fleshy cup or aril. 3. The Strobilus or Strobile.-The fruit of the Hop (Fig. 125) is by some botanists considered as a kind of Cone with membranous scales, to which the name of Strobilus or Strobile has been given; but the strobile differs essentially from the cone, in having its seed distinctly inclosed in a carpel placed at the base of each scale. It should be also noticed that the term Strobilus is also frequently employed as synonymous with Cone. 4. The Sorosis is a collective fruit, formed of a number of separate flowers firmly coherent into a fleshy or pulpy mass with the floral axis upon which they are situated. An example of this fruit may be seen in the Pineapple (Fig. 123), where each square portion represents a flower; and the whole is surmounted by a crown of empty bracts. The Mulberry is another well-known fruit which presents an example of the sorosis." The Syconus is a collective fruit, formed of an enlarged and more or less succulent receptacle, which bears a number of separate flowers. The Fig is an example of a syconus. In this, the flowers are almost entirely inclosed by the enlarged hollow, pear-shaped receptacle, and what are commonly called seeds are in reality one-seeded fruits resembling achenia. SECTION 6. THE OVULE AND SEED. Having now described the nature, structure, and general characters of the gynoecium or unimpregnated pistil, and the fruit or fertilized gynoecium, we pass to the description of the bodies contained respectively within them, namely, the Ovule and Seed. I. The Ovule.-The ovule is a small, pulpy body, borne by the placenta, and which when fertilized becomes the seed. It is either attached directly to the placenta, when it is said to be sessile, or indirectly by a stalk called the funiculus, when it is described as stalked. The point of attachment of the ovule to the placenta if sessile, or to the funiculus when stalked, is termed the hilum. The ovules are commonly inclosed in an ovary, but in all plants of the Coniferæ, Cycadaceæ, and allied orders, they are situated on the margins of leaves, or at the base of indurated bracts or open carpellary leaves. Such ovules are therefore termed naked, and, as the seeds are also naked, such plants are called Gymnospermous; while those in which the ovules are distinctly inclosed in an ovary are called Angiospermous. It should be noticed, however, that there are some plants in which the seeds become partially naked in the course of the development of the ovary into the fruit, as in the Mignonette; these should be carefully distinguished from true Gymnospermous plants, or those in which the ovules are naked from their earliest formation, as the latter character is always associated with important structural peculiarities in the plants themselves, as we have already noticed in treating of the stem and other organs. Other important differences will also be described hereafter, and more especially in the Physiological part of this volume, under the head of Reproduction of Gymnospermia. Number and Position of the Ovules.-a. The number of ovules in the ovary, or in each of its cells, varies in different plants. When there are more than one, the number may be either few or definite, in which case the number is indicated; or the ovules may be very numerous, when they are said to be numerous or multiovulate. b. Position. The position of the ovules with regard to the cavity or cell in which they are placed is also liable to vary. Thus, when there is but one ovule, this may arise at the bottom of the ovary or cell and be directed toward the summit, as in the Compositæ, when it is said to be erect; or it may be inserted at the summit of the ovary 154 STRUCTURE OF OVULES. and be turned downward, in which case it is inverse or pendulous; if attached a little above the base, and directed obliquely upward, it is ascending; or if it arises a little. below the summit, and is directed obliquely downward, it is suspended; or if from the side of the ovary, without turning upward or downward, it is horizontal. Development and Structure of the Ovule.-The ovule first appears on the placenta as a little roundish cellular projection, which gradually enlarges and acquires a more or less ovate or conical form, and constitutes the nucleus (Fig. 183) of the ovule. This nucleus is at first perfectly uniform in texture and appearance, presenting no cavities except those of the ordinary parenchymatous cells of which FIG. 183. FIG. 184. FIG. 183.—Ovule of the Mistletoe (Viscum album), consisting of a naked nucleus. FIG. 184.-The same ovule cut vertically to show the embryo sac, c, in the nucleus, n. it is composed, and having no integuments; but as development proceeds a special cavity is formed at or near its apex (Fig. 184, c, and 187, b), in which the embryo or future plant is developed; hence this cavity is called the embryo-sac. This sac is produced by the special development of one of the cells lying near the center of the nucleus, which, as it continues to increase in size, presses upon the surrounding parenchymatous cells, and occasions their more or less complete absorption. Thus it sometimes causes the almost entire absorption of the nucleus, and even projects beyond it, either through the opening in its coats afterward to be described, called the micropyle (Fig. 187, e), or through its sides in various directions, by which one or more saccate processes are formed. More usually, however, the tissue of the nucleus is not entirely absorbed, but a portion is left surrounding the embryo-sac. The sac contains at first an abundance of semifluid protoplasmic matter, in which, before fertilization, two rounded |