114 THE FROG > OR THE TOAD. 



some of the anterior vertebra. Make out the following divisions of the 

 nervous system in their order: Olfactory nerves, olfactory lobes, 

 hemispheres of the cerebrum, optic lobes, medulla oblongata, and 

 spinal cord. Note also the optic nerves running from the optic 

 lobes to the eyes, and the spinal nerves branching off from the spinal 

 cord. 



Exercise 7. Make a diagram of so much of the nervous system as you 

 have dissected out. 



A more careful study of the circulation may be made by injecting a 

 colored mass of some sort into the ventricle of the heart in a specimen 

 recently chloroformed. The details of this process and study will be 

 left to the student's investigation. A study of the blood circulation in 

 the web of the frog's foot will also prove profitable and interesting. 



If the eggs of frogs and toads are secured in the early spring, or their 

 larvse taken a little later, a study of the development of the tadpole is 

 practicable in a properly arranged school aquarium. 



Exercise 8. Draw tadpoles in various stages of development. 



