EXERCISE LXVIII. Sutures and Dehiscence. LOOK among the ripe and dry pea and bean pods, upon the dry vines, for those that have begun to open. Examine the edges of the separate parts. Do you see something like a joint where the two parts were united? Compare them with Fig. 291. FIG. 291. DEHIS'CENCE.-The opening of a seed-vessel at maturity. See Fig. 291. SUT'URE.--A seam. The line along which dehiscence occurs, and so permits the escape of the seeds. VEN'TRAL SUTURE.--The inner suture of a carpel. The one looking toward the centre of the flower. In Fig. 291, it is the suture along which the ovules are attached. DOR'SAL SUTURE.-The outer suture. See Fig. 291. What name is given to those joints in ovaries at which they open when the seeds are ripe? How many sutures has a bean-pod? To which suture are the beans attached ? When an ovary opens spontaneously, and thus liberates its seeds, it is called a DEHISCENT OVARY. When it does not open, it is an INDEHISCENT Ovary. Are there any indehiscent ovaries among the fruits of the garden or farm? Mention all the dehiscent ovaries you can think of. Again turn to Fig. 197, and compare it with Fig. 292. FIG. 292. Obtain the ripe fruit of IRIS [flower de luce], and compare it with the pictures? Is it a dehiscent or indehiscent fruit? Can you find sutures at which the carpels open? What do you call the suture at which the seeds are attached? What do you call the line in the outer wall of each carpel, opposite the ventral suture? BASE.-The bottom of the ovary. The end attached to the peduncle. Figs. 292, 293. Fig. 292. A'PEX.-The top of the ovary. DISSIP'IMENTS.-The partitions between the cells of syncarpous [carpels united] ovaries. Fig. 293. FIG. 293. Parietes. Base. PARIETES.-The wall of the ovary. Fig. 293. Ax'Is. The central part of the ovary where the ventral sutures join together. a, Fig. 293. EXERCISE LXIX. Parts of Carpels. FIG. 294. VALVES. The parts into which carpels separate by dehiscence. Fig. 294. PLACEN'TA.-The cord along the ventral suture, to which the ovules are attached. It is the "string" that pulls off in preparing string-beans for the table. pl, Fig. 294. Find the placenta in full grown bean and peapods. Find it in little ones where you can just see the ovules. Observe the little stem by which the ovules and seeds are attached to the placenta. By what name is it known? Answer. It is called the FUNICULUS. How many carpels compose it? Point out the sutures? Which is dorsal and which ventral? Find the valves. The placenta. The funiculus. IF INDEHISCENT Can you count the carpels? Look for the ovules or seeds. Point to the funiculus. The placenta. * Point out the base of the ovary. The apex. The axis. The parietes. The dissipiments. |