132 



THE NERVES. 



Dr. B. Yes ; and to be perfectly convinced of this 

 fact, you have only to compare the figure of the 

 fishes' brain with this of man's, representing the 

 form which it possesses when any traces of or- 

 ganization can be first discerned. 



Emily. -Well this is strange indeed ! they 

 seem to be perfectly alike ; at least, I can dis- 

 cern no essential difference. The difference be- 

 tween them however, must be manifested after- 

 wards ; this being the permanent form of the 

 fishes' brain, while in man it is only temporary. 

 Dr. B. It is succeeded by the form of the brain, as 

 it appears in reptiles ; then as it exists in birds ; and 

 finally by that which is destined to be its permanent 

 form. 



Emily. But you also said that in the lowest classes, 

 the nerves were formed before the spinal marrow and 

 brain showed any signs of existence, now is this ths 

 case too, in man ? 



Dr. B.^Most certainly ; the nerves may be seen 

 quite distinctly, while the spinal marrow is yet in a semi- 

 fluid state. When this is fully organized, the nerves 

 extend themselves to its sides, and join it by two divi- 

 sions, called the anterior and posterior roots. This figure 



will give you a little better idea of it, than you can ob~ 

 tain from mere verbal description. Here you see the 



