CHAPTER VIII. 



SUMMARY OF THE FROG 



It has now been seen that the frog is a cold-blooded animal, an am- 

 phibian, and a vertebrate. 



Its external features have been observed. 



Its internal structure consisting of a series of organs known as sys- 

 tems have been studied. These were: 



(a) Digestive. 1 



(b) Circulatory. I Concerned with Metabolism. 



(c) Respiratory. | 



(d) Excretory. 



(e) Nervous. 1 Concerned with regulation and 



(f) Endocrine secretions. J control. 



(g) Muscular. "} , . , t 



uv ci i * i I Concerned with locomotion, 



(h) Skeletal. 



,.*. T support and protection, 



(i) Integumentary. J 



(j) Reproductive. Concerned with the propagation of the 

 race. 



It has been learned that organs are composed of tissues, and tissues 

 in turn, of sheets of similar functioning cells. 



There were four general types of tissues : 



(a) Epithelial. 



(b) Connective. 



(c) Muscular. 



(d) Nervous. 



Tissues may also be classified according to their functional and 

 structural character. For example, according to function, the epithelium 

 is grouped as follows : 



(a) Glandular, which consists of secreting cells. 



(b) Sensory, which consists of sensory nerve cells and their 



fibers. 



(c) Germinal, which consists of those cells having especial 



growth or reproductive ability. 



(d) Protective, which goes to make up an outer covering of an 



organ or of the body itself. 

 According to structure: 



(a) Cuboidal, 



(b) Cylindrical, 



(c) Columnar, 



(d) Squamous, 



(e) Stratified, 



