WHAT IS AN ORGANISM? \TJ 



structure and diffcrcMitiation of parts, called organs, and of 

 the specialization of the functions of these organs 



Classification of the Functions of a Vertebrate. — Analysis of a 

 highly specialized organism, such as a vertebrate, presents us 

 with three groups of functions, viz. ; Sustentation, Genera- 

 tion, and Correlation. 



I. Sustentation, or Assimilation, is seen in the various 

 processes of what we are accustomed to call growth, the tak- 

 ing in and digesting of food, and the building up of tissue. 



In assimilation two kinds of results are attained. The 

 morphologic effects are technically called metabolic changes; 

 these may be divided into changes of two kinds : Constructive, 

 ox Aiiabolisin ; and Destructive, ox Katabolisni. The destruc- 

 tive process, or katabolism, results in two special functions: 

 Secretion, which is the preparation of products necessary to 

 the anabolism, or to the constructive work of the organism ; 

 and Excretion, or throwing off of useless products of the 

 activities of the organism. 



II. Generation, or Reproduction — vegetative multiplica- 

 tion. 



III. Correlation, exhibited in higher organisms in two 

 ways; as {a) Contractility — seen in muscular action, and 

 {b) Irritability — as seen in responses to any exciting cause 

 or sensation. 



In the following table is shown the relation of the systems 

 of organs and special tissues to these groups of functions: 



I. Sustentation. 



(I") Nutritive Alimentary system : mouth, stomach, intestines, etc. 



(P) Circulative Circulatory system : heart, veins, etc. 



[ Excretory organs : kidneys. 

 (!') Purificative ] Respiratory organs : lungs, etc. 

 ^ j Secretory organs : liver, salivary gland, pancreas, 



[ etc. 

 ( Generative organs : ovaries, etc. 



II. Generation -! .■\uxiliary organs : egg-capsules, uterus, mammae, 



( etc. 

 III. Correlation. 



r Muscles. 



/iTT«\ n ,, .,»:,„ Skeletal parts : exo- and endo-skeleton, for fixation 



(111") Contraction \ "^ . . ^ a . i. i ' 



' support, protection, and offence, as teeth, claws, 



[ bones, shell, coral, etc. 



(IIP) Irritability \ Nerve-ganglia : nerves and brain. 

 ^ ■' \ Sense organs : eye, ear. etc. 



