10 GEORGE L. STREETER 
Fig. 3 Topography of the spinal cord and the dorsal root of the first sacral 
nerve in three fetal stages. 'These are taken from three of the same specimens 
shown in figure 2, but here they are shown on one scale of enlargement in order 
to indicate the actual changes in size. The 30-mm. specimen is shown both in 
figure 2 and figure 1. y 
