THE GENERAL ANIMAL FUNCTIONS 89 



(b) Digestion, 



(c) Absorption (from the digestive tract, and at every other 

 cell wall), 



(d) Circulation, 



(e) Assimilation = anabolism, 



(/) Dissimilation = katabolism (including respiration), 

 (g) Secretion and excretion (of waste matter including carbon 

 dioxid). 

 The processes in (o), (6), (c), and (e) are anabolic, i.e., add 

 to the resources of the body. Those in (/) and (g) are katabolic, 

 i.e., tend to destroy the materials, develop energy, and eliminate 

 waste. Circulation contributes to the accomplishment of both 

 purposes. 



5. The supportive skeletal structures may be internal, or 

 external, or both. They may arise as a secretion of the super- 

 ficial cells of the body, or consist of a mixture of cells and in- 

 ter-cellular substance. Their nature and arrangement are 

 profoundly important in determining the distribution of the 

 other more active organs. 



6. Growth and reproduction are the outcome of the nutri- 

 tive processes. Growth is increase in mass ; reproduction is the 

 production of new individuals from old. Reproduction always 

 involves division of a cell (or an organism) and may be asexual 

 or sexual. The latter typically involves two parents. In it 

 two cells, which may be either similar or dissimilar, must unite 

 before development will proceed. In parthenogenesis, only the 

 female parent is necessary. 



7. The nervous and muscular systems are closely related 

 in function. Their united work is to receive, coordinate and 

 respond to the external or internal stimuli affecting the animal. 

 The structures to receive stimuli (end organs) are largely super- 

 ficial; the coordinating and controlling parts (central organ) are 

 deep-seated, thereby securing protection and a central position; 

 the muscular system must have definite relations with the hard 

 parts upon which it acts. Thus arises the necessity of connec- 

 tives or nerves between the various portions. 



8. The sense organs represent areas of the epithelium which 

 are peculiarly adapted to the reception of some one of the forms 



