Unicellular^ Microscopic Animals 367 



(oo-kin'et) (Gr. oon, egg; kine, motile) which enters the wall of the 

 mosquito stomach. Here the ookinete forms a round oocyst (o'osist) 

 (Gr. oon, egg; kystos, sac) which, after six to seven days, forms hundreds 

 of spindle-shaped sporozoites which eventually go to the salivary glands 

 of the mosquito, ready to be transferred by a bite. Formation of spores 

 from a fertilized zygote is called sporogony (spo -rog' o ne) (Gr. sporos, 

 spore; gonos, to produce), but if formed from unfertilized cells it is called 

 schizogony (skiz -og' o ne) (Gr. schizein, to cleave). 



QUESTIONS AND TOPICS 



1. List all the characteristics which protozoa, as revealed by your studies, have 

 in common. 



2. Make a table of the protozoa studied, showing all differences between them. 



3. Explain specifically why certain protozoa are considered as plant-animals. 



4. Describe each of the following for the protozoa studied: (1) integument, 

 (2) motion and locomotion, (3) ingestion and digestion, (4) circulation, (5) 

 respiration, (6) excretion and egestion, (7) coordination and sensory equip- 

 ment, and (8) reproduction. 



5. Why do unicellular protozoa not have organs and tissues? What are such 

 structures called in protozoa? 



6. What characteristics of living protoplasm did you observe in your studies 

 of protozoa? 



7. In the light of the numerous abilities of protozoa to live successfully, would 

 you consider them simple or complex? Explain. 



8. Discuss the economic importance of protozoa, both detrimentally and bene- 

 ficially. 



9. Explain the complex life cycle of such a protozoan as Plasmodium, including 

 the stages in proper sequence, the different hosts, and the detrimental effects 

 of the different stages. 



10. Explain the significance of parthenogenesis as revealed by certain protozoa. 



11. List the conclusions you can draw from the observations made on protozoa. 



SELECTED REFERENCES 



Calkins: Biology of the Protozoa, Lea & Febiger. 



Calkins: The Smallest Living Things, The University Society. 



Calkins and Summers: Protozoa in Biological Research, Columbia University 



Press. 

 Hegner: Invertebrate Zoology, The Macmillan Co. 

 Hegner: College Zoology, The Macmillan Co. 



Hegner and Taliaferro: Human Protozoology, The Macmillan Co. 

 Hyman: The Invertebrates (Protozoa to Ctenophora), McGraw-Hill Co., Inc. 

 Kudo: Handbook of Protozoology, Charles C Thomas, Publisher. 

 Minchin: An Introduction to the Study of Protozoa, Lea & Febiger. 

 Morgan: Field Book of Ponds and Streams, G. P. Putnam's Sons. 

 Needham and Needham: Guide to the Study of Fresh Water Biology, Comstock 



Publishing Co., Inc. 

 Ward and Whipple : Fresh Water Biology, John Wiley & Sons, Inc. 



