GROWTH OF THE CEREBRAL CORTEX 133 
pared by me, from the material fixed in Bouin’s fluid, imbedded 
in paraffine, stained with the carbol-thionine, and projected and 
enlarged by a fixed number of diameters. The size of the pictures, 
therefore, corresponds to the uncorrected measurements given in 
tables 1 and 2. 
Though they are increasing in volume very rapidly after birth, 
the pyramids in the lamina pyramidalis retain up to a brain 
weight of 0.6 gram (VI, 6 days in age) the characteristics of the 
: 
7 a 
Fig. 8 Showing semi-diagrammatically the increase in size and the morpho- 
logical changes, in the typical pyramids in the lamina pyramidalis of the cerebral 
cortex of the albino rat. The Roman number by each cell figure indicates the 
brain weight group from which the typical pyramid was selected and the drawing 
made. All cell figures have been uniformly magnified to 950 diameters, according 
to the uncorrected measurements. 
