262 



BIOLOGY FOR BEGINNERS 



and more nearly fills the cranial cavity of the skull; while the 

 spinal cord is shorter, thicker, and has its branches arranged 

 much more like those of the higher animals. 



Observation of the living frog shows that all the senses are 

 fairly developed except possibly that of taste. Sight and hearing 



ADAPTATIONS OF THE FROG 



By Means of 



For the purpose of 



External features 

 Head 



Limbs 



Digestive organs 



Circulatory organs 



Respiratory organs 



Protective color 



Shape, and slimy secretion 



Large mouth 



Location and shape of 



tongue and teeth 

 Nostrils at tip of nose 



Projecting eyes 



Short fore limbs 

 Long hind legs 

 Very long feet and toes 

 Powerful muscles 

 Webbed toes 



Gullet and mucous glands 

 Stomach and gastric glands 

 Intestine, liver, and pan- 

 creas 



Three chambered heart 

 Veins 

 Arteries 

 Capillaries 



Blood 



Gills in tadpole 

 Two lungs in adult 

 Lung lining cellular 

 Rich blood supply 

 Throat and body muscles 

 Thin vascular skin 



Escape from enemies 

 Locomotion and escape 

 Catching food 

 Catching food 



Breathing when partly sub- 

 merged 



Vision when partly sub- 

 merged 



Landing after leaping 

 Increasing leverage for 



leaping 



Leaping and swimming 

 Swimming 

 Swallowing 

 Digesting proteids 

 Digesting and absorbing all 



food stuffs 



Forcing blood through body 

 Bringing blood to heart 

 Carrying blood from heart 

 Distributing blood to the 



tissues 

 Transportation of food, 



oxygen, waste, CO* 

 Absorbing dissolved oxygen 

 Absorbing free oxygen 

 Increase of absorbing area 

 Carrying oxygen , etc. 

 Taking air into lungs 

 Additional breathing when 

 submerged 



