How To Study Living Animals


2. The Complex or Sexual Method of Reproduction
Materials.

Slides or diagrams showing hydra and sponge reproducing sexually herunterladen. Conjugating paramecia, fertilized and unfertilized starfish eggs.

Directions.

Identify the reproductive organs or gonads of the hydra herunterladen. These are slight swellings on the surface. The one nearer to the mouth end is the spermary and that near the attached end is the ovary.

Questions microsoft office kostenlos downloaden vollversion deutsch chip.

1. How is an egg cell produced in hydra? In general how do the reproductive cells of sponges and hydra originate?

2. What is gained by limiting the process of reproduction to special cells?

3. What is the difference between the appearance of the nucleus of the fertilized and the unfertilized egg?

4. What is the advantage of cross fertilization? How accomplished in Hydra? What reason can you suggest for the spermary’s position?

5. Describe the conjugation of a paramecium.

6. Describe the process of maturation and fertilization in a starfish egg.

Suggested drawings.

a. Diving Amœba or Paramecium.

b. Budding Hydra.

c. Hydra showing gonads.

d. Starfish egg—fertilized and unfertilized.

Summary of important points in the study of methods of reproduction:—

1. What are the two principal methods of reproduction? How do they differ?

2. Why is reproduction necessary?

B. Development