636 C. JUDSON HERRICK AND JEANNETTE B. OBENCHAIN 



apparatus and transferred to wax plates, from which a model of 

 both sides of the brain was constructed magnified 75 diameters. 



This model includes the entire brain back to a point between 

 the superficial origins of the Vth and Vllth cranial nerves, save 

 for the omission of the choroid plexuses of the mid-brain and 

 medulla oblongata. In the telencephalon and diencephalon thin 

 wax plates were used which were almost exactly seventy-five 

 times the thickness of the sections, so that almost every section 

 is represented in the model, which preserves in this region the 

 ventricular sculpturing with all possible accuracy. As the plates 

 were stacked, measurements were made with callipers after the 

 addition of each group of five plates and thus the cephalo-caudal 

 length of the model was controlled by comparison with the com- 

 puted length required by the magnification chosen. This control 

 required the omission of two plates, one in front of the lamina 

 terminalis and one in front of the posterior commissure. With 

 these two exceptions the model contains all of the sections of the 

 series from the anterior end of the brain to a point behind the 

 posterior commissure. Behind this level somewhat thicker plates 

 were used. This, however, involves no loss in accuracy, since the 

 superficial structures of the mid-brain and oblongata are larger 

 and more easily defined than are those of the thalamus. After 

 carefully stacking the plates, they were cemented sufficiently to 

 hold them together. The right and left halves were then cut 

 apart in the medial plane with a silk thread and the halves 

 strengthened with wire stays sunk into the cut surfaces of the 

 wax only, so that the ventricular surface, which presented a very 

 good appearance, might be studied unaltered in any detail. The 

 ventricular surfaces were left untouched until after the comple- 

 tion of the study, which included a careful microscopic examina- 

 tion of all of the sections to determine what deep structures are 

 related to each superficial eminence and groove. ^ ' 



A dorsal view of the model is seen in figure 1. 



^ The labor of preparing and drawing the sections, transferring the drawings to 

 the wax plates and cutting the plates was performed entirely by Miss Obenchain, 

 who at that time had not studied the material nor familiarized herself with the 

 morphological problems involved. The plates, as stated above, were stacked be- < 



