XXVITT. LIFE PEOCESSES OF ANIMALS 



In our study of the animal kingdom we have seen that 

 certain processes, necessary to the hfe of the intlividual and 

 to the perix'tuation of the species, go on in the body of 

 every animah Since the Hfe of the animal and the future 

 existence of its kind depend upon these pi-ocesses, they have 

 licen termed the life processes. Among the more important 

 are ingestion, digestion, secretion, excretion, respiration, 

 circulation, and reproduction. 



Ingestion. — The combined activities of pi-ocuring, mas- 

 ticating, and swallowing food may be termed ingestion. 

 Without food, the animal would soon die. Therefore, 

 every animal is provided with some means of obtaining it 

 and [passing it to the organs of digestion. When the amcpba 

 touches a hit of food, the protoplasm of the liod}' simply 

 incloses the jjarticle, for this animal has no mouth or s]:)eciai 

 organs for ingesting food. The cilia of the ]iaraniecium 

 and vorticella create currents of water that bring food into 

 the mouth. Food is brought to the sponges by the currents 

 of water flowing through the body. The hydra, .sea anemone, 

 and coral ])olyps gather food and ])ass it into the mouth 

 with the tentacles. The tapeworm absorbs its food thrcnigh 

 the skin, l]ut the earth\\'orm swallows (|uantities of soil 

 from which the food ))articlcs ai-e extractcnl. InsiM'ts have 

 biting and sucking iiuiuth parts for obtaining their food. 

 Fish have jaws armed with teeth, while toads (ollect their 

 food with the tongue and swallow it \\hole. The snakes 



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