699. What has perished in a hollow tree?

700. Name the three layers of the bark.

701. The liber - of what tissues? Whence is its toughness?

702. What is the green bark? What its structure?

703. The brown bark - what are its varying colors? What is its tissue?

How is it in the cork oak? 705. Define the medullary rays. What is their structure?

707. Why are they called the silver grain? Show it in figs. 597, 598.

708. What good purpose do they serve?

709. Where is the cambium layer found? What is it?

710. Why is it called the generative layer?

711. Why is the growth of Exogens unlimited?

712. Why is the bark most sought in medicine, etc.?

713. What of a cross-section of an endogenous stem?

714. Explain particularly its structure.

715. As to these bundles - of what does each consist?

717. Has the Endogen a true bark? Why does it split with difficulty?

718. Why are these plants called inside-growers, or Endogens?

719. Why is the caudex of the palmetto, etc., often smaller at base?

720. In what plants is the acrogenous structure found? Why are they so called, i. e., point growers?

721. How does a cross-section of one of them appear? (Fig. 600.) Here describe the figures 595 and 596.

722. What is the rank of the mass-growers? What is their only tissue? What semblance of stems have they?

724. What can you say of the fibrillae of the root? (See the fig.)

725. What may be said of the pileorhiza? Show it in the figures.

726. How does the root grow, and penetrate the soil?

729. What is the substance of the veins?

730. How many layers of the parenchyma are there? When are the two alike, and when unlike?

732. What is the normal place of the stomata? How in floating leaves?

733. What is the condition of the chlorophylle?

734. The vessels of cienchyma - where, and of what use?

Explain fig. 604, and show the parts, as the epidermis, the two layers, chlorophylle, spiral vessels, stomata, etc.

Chapter V

736. What inquiries are we now to start?

738. What problem remains unsolved? What phenomena do we refer to the vitality of the plant?

739. What is the lowest form of life? Whence does it spring?

740. How prove that the vegetable kingdom is subordinate? 742'. In what steps does the process of vegetation consist?

What are the vital phenomena included in vegetation?

744. What two kinds of organic matter make up the cell?

Write out the symbols of these two. Which resembles animal matter?

745. What does the cell imbibe? From what fluid?

746. What chemical decomposition ensues? What becomes of the water formed? What of the cellulose?

747. How is chlorophylle formed? What becomes of the excess of the cellulose? What globule within a globule?

749. What becomes of the excess of protoplasm?

750. What per cent. of gluten and starch in wheat? Why is extra flour deficient in gluten?

751. Can a plant consist of a single cell? Give an example.

752. Describe the two modes of cell growth.

753. How is growth distinguished from reproduction?

754. What is the embryonic vesicle? Its origin? Its destination?

755. How does it receive its impulse in this direction?

756. Trace the growth of the pollen grain after it falls on the stigma.

757. Trace the course of the pollen tube, and in fig. 607.

758. Show the process of growth in the fertilized cell, and in fig. 608.

759. How does Schleiden's view differ from the above? Explain fig. 609.

760. In the Coniferae, where does the pollen fall?

761. What is the state of the embryo in the mature seed? What store is laid up for it?

762. What chemical changes ensue? What is diastase? Dextrine? Whence is the yeast? The heat? The sugar?

766. In the process of ripening fruits, what material is formed?

767. Whence is the honey in the flower? What the use of the sugar?

768. Of what use is the honey to the plant?

Chapter VI

770. What the subject? What is the most important office of the root?

771. Illustration, by a plant of spearmint, hydrangea, etc.

772. What organs absorb the water in these cases?

773. Illustrate this by a radish plant.

774. In transplanting trees, what special care must be used?

775. What of the force of this absorption? How may it be shown?

777. Name the two causes of the ascent of the sap.

778. Illustrate capillary attraction by glass tubes. By a napkin.

780. Illustrate endosmose by dried prunes.

781. Illustrate by a bladder and long glass tube.

784. Of what use to the vegetable is absorption? Have the roots the power of choice? Give examples.

785. What other organs absorb? What illustrations are given?

787. In what direction is the flowing of the sap?

788. How does it advance in the tissue of a Cryptogam?

789. In higher plants, what is noticed in the different tissues?

790. What vessels and passages convey air only?

791. What seems to be the moving force which raises the sap?

792. Through what tissue does the sap chiefly ascend?

793. Through which layers, and why?

794. What is the composition of the crude sap?

795. How do you account for the issue of sap from the sugar maple in early

Spring? What causes the flow to cease?

796. How does the crude sap become the true sap?

797. Trace the distribution of this fluid as it returns from the leaves.

798. Specify the places where this sap makes deposits.

799. In what direction is the growth, from above or from below?

800. Illustrate this by the girdling process. Why docs the tree die?

801. Illustrate by a ligature. Illustrate by a wound in the trunk.

803. What the effect of cutting a branch just below a node?

804. What of girdling a potato plant? Fruit tree? Why?