100 



ZOOLOGY. 



The last four cervical (5th to 8th) and first thoracic branch 

 out and unite in different combination, so forming the 

 brachial plexus, from which come the important nerves 

 of the arm. Similarly, the last four lumbar and first two 

 sacral give rise to a lumbo-sacral plexus, from which the 

 main nerves to the leg are formed. 



6. The Brain of the rabbit is a highly complex 

 structure, and the difficulties of understanding it are 



Fig. 54. BRAIN or RABBIT. 



A, Dorsal view; B, Ventral view. (After Wiedersheim.) 



aggravated by the nomenclature of its parts, which is 

 largely based on the very fanciful ideas of the older 

 anatomists on the still more complex human brain. For- 

 tunately, a new nomenclature, based on a more rational 

 system, has grown up of late years; but the old terms 

 have still to be learned. 



As already mentioned, the central nervous system is 

 at first a tube of nerve-tissue. The anterior end, which 



