the wax scale and roam about over the orange tree.  Finally, they settle down, thrusting their sucking beak into the plant tissue, and cast their skin.  The females lose at this molt their legs and eyes and feelers.  Each becomes a mere motionless sack capable only of sucking up sap and laying eggs.  The young males, however, lose their sucking beak and can no longer take food, but they gain a pair of wings and an additional pair of eyes.  They fly about and fertilize the sacklike females, which then molt again and secrete the thin wax scale over them.

Throughout the animal kingdom loss of the need of movement is followed by the loss of the power to move and of all structures related to it.

—­Jordon and Kellogg:  Animal Life.

Has the principle of unity been observed in the above selection; that is, of the many things that might be told about a sea squirt, a barnacle, or a scale bug, have the authors selected only those which serve to illustrate degeneration through quiescence?

Instead of one generalization supported by a series of facts to each of which a paragraph is given, we may have several subordinate generalizations relating to the subject of the theme.  Each of these subordinate generalizations may become the topic statement of a paragraph which is further developed by giving specific instances or by some other method of paragraph development.  Such an order, that is, generalization followed by the facts which illustrate it, is coherent; but care must be taken to give each fact under the generalization to which it is most closely related.  On the other hand, our theme may be made coherent by giving the facts first, and then the generalization that they establish.

+Theme XLIX.+—­Write a theme of three or more paragraphs illustrating or proving some general statement by means of facts or specific instances.

Suggested subjects:—­
    1.  Young persons should not drink coffee.
    2.  Reasons for the curfew bell.
    3.  Girls wear their hair in a variety of ways.
    4.  There are several kinds of boys in this school.
    5.  Civilization increases as the facilities for transportation
        increase.
    6.  Trolley roads are of great benefit to the country.
    7.  Presence of mind often averts danger.

+92.  Development of a Composition by Stating Cause and Effect.+—­The statement of the causes of an event or condition may be used as a fifth method of development.  The principle, however, is not different from that applied to the development of a paragraph by stating cause and effect (Section 49).  If several causes contribute to the same effect, each may be given a separate paragraph, or several minor ones may be combined in one paragraph.  For the sake of unity we must include each fact, principle, or statement in the paragraph to which it really belongs.  The coherent order is usually that which proceeds from causes to effects rather than that which traces events backward from effects to causes.