CHABACTEKISTICS OF ANIMALS 27 



the period of growth: most small animals develop completely 

 in a year; horses take four to five years; man approximately 

 twenty-one years. The average height of man is 5 feet, 8 inches. 

 The average weight of the horse iS between 1000 and 1100 pounds. 

 Giants and dwarfs are always abnormal productions and repre- 

 sent pathologic changes. These abnormalities are not trans- 

 mitted to the offspring. The feeder of animals should aim to 

 get the maximum growth each day for, as has been stated, growth 

 ceases after a certain age. 



9. Reproduction is probably the most remarkable and interest- 

 ing of all the processes of living matter. It represents the power 

 to produce new but similar individuals. Detailed consideration 

 of this process will be postponed until the reproductive organs 

 of the body have been studied, when it can be more easily 

 understood. 



10. Response to environment is the power that induces the 

 production of substances that help to neutralize disease and to 

 repair wounds, and adapts the body to its physical surroundings. 



The possession of these processes make cells highly efficient 

 energy-transformers, and admirably adapted to the important 

 work that they perform. 



Besides the cells, the body is composed of a framework of 

 intercellular substance. If all the cells were removed there would 

 still remain connected meshes like basket work that would 

 represent the whole form of the body in all its parts and much 

 of its solidity would remain. This intercellular substance, 

 which varies in character in different places, comprises much of 

 the skeleton and the bulkier part of all connective tissues which 

 permeate all tissues and organs. 



THE TISSUES OF THE ANIMAL BODY 



A tissue is a collection of more or less similar cells possessing 

 functions somewhat alike. Body tissues are divided into the 

 vegetative tissues, which support, bind together, protect, and 

 nourish; and the master tissues, which control the body. 



A. The vegetative tissues may be separated into (I) epithelial 

 tissues and (II) connective tissues. 



I. Epithelial tissues consist of large numbers of cells and a 

 very small amount of intercellular or cementing substance, so 

 they fit together very closely. They develop from the 



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