522 NAOKI SUGITA 



time and that at 56°C. in summer time, for the convenience of 

 making sections. 



A series of sections 10 micra thick was cut exactly from the 

 designated level, adjusting the microtome carefully to this end, 

 and these sections were affixed on the glass slide by the albumin- 

 glycerine method. After the sections had dried in the oven over- 

 night at 37°C., they were washed in the xylol bath, in order to 

 dissolve away the paraffine from the sections, and then again 

 washed with absolute alcohol to remove the residual xylol. 

 After having passed through the several grades of alcohol, they 

 were brought to the water bath, and kept there until the yellow 

 tone of the sections due to the picric acid in Bouin's fluid totally 

 faded away. Now the sections were placed in the carbol-thionine 

 solution above described and remained there for two hours at 

 room temperature. After being washed slightly with running 

 water, and passed through 70 per cent, 80 per cent, 90 per cent, 

 95 per cent and absolute alcohols successively, each for a short 

 time, in which they were not only dehydrated but at the same 

 time decolorized, they were cleared in xylol or carbol-xylol and, 

 at last, mounted in the neutral Canada balsam. 



Examination of sections 



The sections were each projected on a sheet of paper by the 

 Leitz-Edinger projection-apparatus, at a magnification of twenty 

 diameters exactly. The outline of the image was then accurately 

 traced on the sheet, and, perpendicular to the braii;! surface, 

 fines were drawn parallel to the radiations of the cortex at sev- 

 eral selected localities, at which the thickness of the cortex was to 

 be measured. These localities are shown on the figures which 

 will be described in the following chapter. The length of the 

 line between the external margin and the lowest cell-layer of the 

 cortex, where it is in contact with the white matter, was measured 

 with the sfiding calipers accurately to a tenth of a millimeter, 

 and one twentieth of this value was recorded as the actual thick- 

 ness of the cortex on the sfide at this locality. 



