404 AXATOJUC'AL TECHNOLOGY. 



triculus lateralis. Proplexus— Plexus ventriculi lateralis. Prosen- 

 cephalon — Cerebrum, hemisijliserse. Pseudo-commissura — Connec- 

 tive tissue between lobi olfactorii in Anura. Rhinencephalon — Lobi 

 olfactorii. RhinoccBlia— Ventriculus olfactorius. Terma — Lamina 

 terminalis, lamina cinerea. Tuber cinereum. Thalamus — Tliala- 

 mus nervi optici, wall of diacoelia. Valvula — Valve of Vieussens. 



§ 1059. List of some of the I'echnical Names of the Parts most frequently mentioned, 

 with the terms (in black letter) ichich are Preferred to them. — Aquaeductus Sylvii — Meso- 

 coelia. Chorda 8[ inalis— Myelon, Commissura anterior — Praecommissura. Commig- 

 sura posterior — Postcotnmissura. Corpus pineale — Conarium. Corpus pituitarium — 

 Hypophysis. Ependyma — Endyma. Foramen Mouroi — Porta. Iter a terlio ad ven- 

 triculum quartum — Mesoccelia. Lamina terminalis s. cinerea — Terma. Lobus opticus 

 — Opticus. Medulla oblongata— Metencephalon. Pedunculus cerebri — Crus cerebri. 

 Plexus choroideus ventriculi tertii — Diaplexus. Plexus choroideus ventriculi lateralis — 

 Proplexus. Ventriculus lateralis — Procoelia. Ventricle of the " unpaired cerebral rudi- 

 ment," mesal part of ventriculus lobi communis — Aula. Ventriculus quartus — Meta- 

 ccelia. Ventriculus tertius — Diacoelia. 



Comparative Brevity of the Terms here adopted. — In the above list there are 19 new names 

 composed of 20 words and about 150 letters. The corresponding old names comprise 40 

 words and about 300 letters. Since the parts specified are very frequently mentioned in 

 treating of the macroscopic anatomy of the brain, it is evident that a substantial saving is 

 effected by the employment of the shorter terms. 



§ 1060. The EncepTialic Segments. — All brains present more or 

 less marked constrictions with intervening enlargements ; the caudal 

 region also is single or mesal, while the cephalic is double or in two 

 lateral parts. Hence the brain may also be defined as an incom- 

 pletely segmented tiibe of nervous tissue, Mfurcated at one end. 



In each of these segments there is one organ or pair of organs 

 constituting its principal or characteristic portion, but there are 

 always some other parts of greater or less importance. 



§ 1061. Names of the Encephalic Segments. — That region of the 

 brain which includes the {lohi) optici, which is easily recognized in 

 most adults and is very prominent in the embryo, has been almost 

 uniformly designated by the technical term mesencephalon, or by 

 its vernacular equivalents mittelhirn or midbrain. 



With regard to all the other segments, however, there has been 

 such diversity of usage that the student is apt to be confused in 

 comparing the statements of different writers. In the following 

 Table are given the principal synonyms of the names of the ence- 

 phalic segments herein adopted, which, as may be seen by compar- 

 ing the second and seventh columns, are almost identical with those 

 which are given in the Human Anatomy of Quain (A). 



