STUDY OF STRUCTURE OF CENTRAL NERVOUS SYSTEM. 15 



of the temporal lobe. This is the inferior horn. A posterior horn 

 arises from the inferior horn and extends into the occipital lobe. 



In tlie floor of the anterior horn, note on the outer side: 



1. A large, rounded eminence tapering oft' behind. This is the intraventri- 

 cular part of the corpus striatum, caudate nucleus. 



Internal to this: 



2. The choroid plexus of the lateral ventricle which enters by way of the 

 foramen of Munro and extends to the tip of the inferior horn. 



3. Internal to and behind this a rounded eminence, the hippocampus. Snip 

 off' a piece of the surface of this and note that the main mass is gray matter, the 

 white being a thin layer covering it. Note diff'erences in the brain ventricles. 



Make vertical, transverse sections (coronal) of one half-brain: 1. Just 

 behind the olfactory bulb. 2. Just in front of the knee of the corpus 

 callosum. 3. Through the middle of the infundibulum. 4. Through 

 the corpora albicantia. 5. Through the superficial origin of the III 

 nerve. 



Study these in connection with similar microscopic sections at the 



. same time that the dissection of this basal region is made. Observe 



especially the optic thalamus, caudate and lentiform nuclei, with the 



internal and external capsule and claustrum forming the corpus striatum. 



At this point the dissection of the brain by Johnston's method (3) may 

 profitably be undertaken, using the outline he gives in so far as the 

 somatic and visceral divisions are concerned. The greatest objection to 

 Johnston's outline is that he overemphasizes the olfactory apparatus, 

 devoting two pages to this and only seven pages to the whole remaining 

 structure of the central nervous system. 



The work previously outlined has been most successfully carried 

 through by giving one hour periods each day for two weeks, but it may 

 be condensed into longer periods each day for a shorter time. Ad- 

 ditional work, such as the making of models from macerated scrap paper 

 and flour paste by the method of Mendoza, Eamirez, and Valencia (5), 

 may be done after having finished the brain dissection according to 

 Johnston's outline. 



Students in the Philippine Medical School who are well advanced may 

 undertake elective work of this kind or they may work on original 

 problems suggested by previous studies. During the intersessional vaca- 

 tion the majority of them elect some special topic for investigation, and 

 devote six weeks to an occupation that is particularly refreshing and 

 zestful. 



The surface morphology of the brain is studied as follows (tliis, if 

 expedient, should precede Johnston's method of brain dissection) : 



Take a human brain and study the lobes, fissures and convolutions. 



1. The lateral fissure (Sylvius). 



2. The central fissure of Rolando. 



3. On the mesial surface the occipito-parietal fissure. 



