THE LOWER BRAIN. 



491 



the complemental processes that the functions of the hemispheres 

 demand. 



The annexed colored plate, which represents a median and 

 vertical section of the encephalon and bulb of a three months' 

 embryo, distinctly indicates the direct continuation of the 

 cord up to the posterior or infundibular pituitary lobe. The 

 tract connected with the posterior pituitary is colored bluish 

 gray. The pituitary has been added to the infundibular ex- 

 tremity of the original illustration. The relations of the 

 structures which ultimately become the corpora quadrigemina 

 by meeting the posterior part of the third ventricle are well 

 shown. 



That our views in this connection are based on a solid 

 foundation is further sustained by the painstaking investiga- 

 tions of Andriezen, 5 who traced a direct connection between 

 the pituitary and the medullary and other more anterior struct- 

 ures through the various phylogenetic stages of vertebrates. 

 The following statements and the table appended are quoted 

 from his paper: "A survey and investigation based on all 

 classes of vertebrates show that the hypophysis occupies the 

 position and relationship to the other structures which may 

 be condensed in the following table: 



"RELATION OF PITUITARY TO OTHER NERVE-CENTERS AND 

 HEAD- STRUCTURES IN ORDER FROM BEFORE BACK. 



Andriezen: British Medical Journal, Jan. 13, 1894. 



