HOW IS MAN'S BODY CONTROLLED? 



429 



force of gravity when sand grains were in the statocysts. This 

 showed that the statocysts are balancing organs. 



Light-receiving devices are of various kinds, from the simple 

 eyespot in Euglena or small groups of sensory cells to the com- 

 plicated compound eye of insects and the camera-like structure 

 of man's eye. 



Practical Exercise 2. Fill in the following table, listing the various kinds 

 of sensory structures found in each animal you have studied. 



AXIMAL 



Structure 



Where Found 



How Used 













- 















Self-Testing Exercise 



In higher animals, (1) from special structures carry 



(2) to organs of movement which bring about (3). When an 



animal (4) moves away or toward the (5), the re- 

 sponse is a (6) . Light-receiving devices vary from the 



(7) in (8) to the (9) (10) in man. 



PROBLEM IV. HOW IS MAN'S BODY CONTROLLED? 



Laboratory Exercise. The anatomy of the nervous system. In a 



frog from which the organs of the body cavity have been removed, 

 note the white glistening cords (nerves) which seem to come from 

 under the backbone. Follow the course of some of the larger nerves. 

 To where do they lead? Now turn the frog over and with sharp 

 scissors and a scalpel remove very carefully the bony covering (the 

 skull) from the whitish body (the brain). 



How many parts appear to be in the brain? Notice the white 

 elongated hemisphere of the forebrain or cerebrum. 1 The two anterior 

 projections of the cerebrum are called olfactory lobes. Where do these 

 lobes seem to lead ? What do you think, from the name, their use is ? 



Just back of the cerebrum, find two large lobes, known as optic 

 lobes, which have to do with sight. Look at the chart. Are the eyes 

 connected with the optic lobes? Back of the optic lobe we find the 

 cerebellum 2 and medulla, 3 the latter running directly into the spinal 

 cord, from which rise the spinal nerves you have noted. 



Cerebrum : ser'e-brum. 



2 Cerebellum : ser'e-beTwm. 



Medulla: me-dul'a. 



