STRUCTURE OF THE CORTEX CEREBRI. 
61 
Summary. 
In conclusion it will be well to summarise briefly the chiefs facts of interest which 
have resulted from these investigations. These may be stated as follows :— 
1. A five and a six-laminated cortex is found in all the animals examined. 
2. The fundamental structure of the layers is very similar in all. 
3. Divergence in type is induced through varied character and distribution of the 
elementary units of these layers. 
4. As in Man so in other animals variations in laminar type centre about the mid¬ 
regions of the cortex. 
5. The ganglionic series is arranged upon grouped and laminar type. 
6. The five-laminated cortex and nested cells are characteristic of motor areas. 
7. Transition realms are readily recognisable in the Pig. 
8. The first layer of the cortex in the Pig is deeper than in animals higher in the 
series and is crowded with Deiter’s corpuscles. 
9. There is great uniformity in size of the cells of the third layer in the Pig. 
10. The six-laminated type is formed by the intercalation of a belt of small angular 
and pyramidal elements. 
11. Great uniformity in contour and complexity of cells is observed throughout the 
ganglionic series in the Pig and Sheep. 
12. The contour of these cells is almost invariably that of an elongated pyramid in 
these two animals. 
13. The ganglionic series is distinguished from the third layer by the interposition 
in six-laminated realms of a belt of angular cells. 
14. The area of five-laminated cortex in the Pig extends over the great limbic and 
frontal lobes and the first and second parietal gyri. 
15. The intimate structure of the brain of the Sheep closely resembles that of 
the Pig. 
16. The crucial sulcus at its origin indicates the transition from the one form of 
lamination into that of the other. 
17. The cells of the third layer in the Cat increase in size with their depth. 
18. The ganglionic cells of the Cat are of great size, and closely crowded around 
the crucial sulcus. 
19. Their arrangement in the limbic and parietal boundaries of the sulcus differ. 
20. Whilst the limbic and frontal lobes in the Pig, Sheep, Cat, and Ocelot have 
areas of the five-laminated cortex, greater variation is found in its disposition over the 
parietal regions. 
21. The main feature of importance observed in the regional distribution of the 
ganglionic series in the Carnivora is its concentration around a limited area embracing 
the crucial sulcus ; in Man and the Ape its wide-spread area conjoined to great 
variations in developmental complexity ; and in the Pig and the Sheep its wide-spread 
distribution conjoined to a notable uniformity throughout in complex relationships. 
