QUANTITATIVE BTUDY OF THE PURKINJE CELLS 237 



METHOD OF STUDY 



The purpose of this study, as has been stated above, was to 

 ■compare the number of Purkinje cells in different types of brains, 

 and also to find what numerical differences, if any, exist between 

 different areas of the same cerebellum. Reasoning by analogy 

 from what is known of the cell losses in the cerebrum, it seemed 

 not improbable that some areas might be found more subject to 

 degeneration than others, and, in view of the localization theory 

 of Bolk, it appeared all the more desirable to make a comparison 

 of the different areas to which different functions have been 

 credited. For this purpose each hemisphere has been divided 

 into six areas, 2 as shown in figure 2. 



1. Lobus anterior (Bolk); head area; the region anterior to 

 the sulcus primarius {S. pr.) 



2. Lobulus simplex (Bolk); neck area; from the sulcus 

 primarius to the sulcus postclivalis (S. pel.) 



* 3. Lobulus semilunaris superior; arm area; from the sulcus 

 postclivalis to the sulcus horizontalis magnus (S.h.m.) 



4. Lobulus semilunaris inferior; arm or leg area; from the 

 sulcus horizontalis magnus to the sulcus pregracilis {S. prg.) 



5. Lobulus graciUs; leg area; from the sulcus pregracilis to the 

 sulcus postgracilis (S. psigS) 



6. Lobulus biventer; leg area (?); part posterior to the sulcus 

 postgracilis, exclusive of the amygdala. 



In order to secure exact and strictly comparable measurements 

 of the relative numbers of cells in these different areas and of 

 the relative numbers in the same areas of different cerebella, the 

 following method has been used: 



The sections were projected at a magnification of 30 diameters 

 by means of the Edinger projectoscope, and tracings made in 

 pencil of the line of Purkinje cells to be counted. The length 

 of this line as traced was measured in millimeters by means of a 

 map measurer. This divided by 30 gave the actual length of 



2 The first two designations (1-2) are given according to Bolk '05 while the 

 remainder (3-6) are those used in Quain's Elements of Anatomy, vol. 3, Neu- 

 rology, part 1, eleventh edition, 1908. 



