11. In a summarizing statement explain any variations you find in the pectoral and pelvic girdle for strength (rigidity); flexibility. This answer may be written as a table, naming the bones, opposite each stating its condition, and then what it affords or is adapted to. 12. What is accomplished by having two bones in the shank of the leg? In what types or forms is there but one, and which one is it? 13. Can you assign any advantages in power, agility, length of leg, or position of leg and foot accruing from a long ankle? (See horse, frog, _et al._) 14. Enumerate the types or forms, and opposite each state the number of fingers and toes. 15. Make a table, heading one column "Form or type"; another, "Habitat"; and a third, "Habit." Judging from the structure which you see or from your previous knowledge or experience, fill in the table, stating whether the type is aquatic, terrestrial, or aërial; whether it burrows, walks, runs, or climbs, etc. 16. From your statements in 15, explain how the peculiar mode of life affects the structure of these types. CHAPTER VII ADAPTATIONS FOR THE PRESERVATION OF THE SPECIES #A. METHODS OF REPRODUCTION# 1. The Simple or Asexual Method of Reproduction _Materials._ Slides or diagrams, showing a dividing amœba, a dividing paramecium, a dividing vorticella, reproduction in some form of sporozoa, budding hydra, gemmules of spongilla, and some species of worm as Dero or Nereis in the process of dividing. _Definitions._ _Spore_, a cell capable of developing into a new organism. _Asexual reproduction_, reproduction by division of the cell or body. _Sexual reproduction_, reproduction by means of the conjugation of two reproductive cells known as the egg and sperm cells. _Fertilization_, the fusion of the male or sperm cell with the egg or female cell. _Ovary_, an organ producing eggs. _Spermary_, an organ producing sperm cells. _Cross fertilization_, fertilization in which the sperm and egg cells are produced by different individuals. _Diœcious_, the different kinds of reproductive organs found in different individuals. _Monœcious_, the different kinds of reproductive organs found in the same individual. _Directions._ _Note._--Refer to your notes, if the animals mentioned in these exercises have been already studied. This exercise may be largely review. Study the methods of reproduction in the specimens or diagrams before you. Determine first, in what respects the methods of reproduction are similar in all; second, in what respects there is a variation. _Questions._ 1. What has an amœba gained by dividing? What powers has each new cell that the original amœba had lost? What would have been the fate of the amœba if it had not divided into new cells? 2. What various forms of cell division did you find? 3. What is the simplest method of reproduction? 2. The Complex or Sexual Method of Reproduction _Materials._