288 ELEMENTARY ZOOLOGY. 



finger-like pouches of its wall (cczca) near its opening into 

 the intestine. These secrete digestive juices, and possibly 

 assist in absorbing food. Fishes have a liver which may 

 have a bile duct connecting with the intestine. 



298. Nervous System and Sense Organs. While the 

 brain is less developed in the fishes than in the other verte- 

 brates, it is probably more complex than in any form 

 we have studied yet. That part of the nervous matter 

 inside the cranium is known as the brain. It has right- 

 left symmetry. Beginning at the front there is a small 



FIG. ii2. Brain of fish, side view, cb, cerebellum; c, cerebrum; o, olfactory lobe; o/, 

 olfactory nerve; on, optic nerve; of, optic lobe; m, medulla oblongata. 



Questions on the Figure. What is the meaning of the terms 

 applied to the parts in the figure? What is suggested by the fact 

 that the brain is in lobes? What is believed to be the particular 

 functions of the various regions ? 



pair of olfactory lobes supplying the sense of smell. These 

 are connected by stalks to the next lobes (cerebrum or 

 forebrain) . Behind these are a somewhat larger pair 

 of lobes (optic lobes) which control vision. Back of the 

 optic lobes is a single lobe known as the cerebellum and 

 behind this the medulla oblongata, which tapers into the 

 spinal cord. From the medulla and the spinal cord the 

 chief nerves of the body arise, except those of smell and 

 sight. The function of the forebrain appears to be to 



