Cell Lamination of Cerebral Cortex of the Lemur. 489 
The specimens in the first place were hardened in formalin. The small 
blocks were passed through several changes of alcohol of gradually increased 
strength, dehydrated in absolute, cleared in xylol, and imbedded in paraftin. 
Sections 10 in thickness were cut in series and numbered, and about one 
section in every 20 was stained, the Nissl or the polychrome methylene 
blue method being used. 
To map out the various areas, their extents were first marked on the 
plans of the sections (vide figs. 3 and 4). By applying these plans to the 
diagrams of the surface of the brain, fig. 1 has been composed. 
The drawings of the types of cortical lamination (Plates 14—18) were made 
with the camera lucida, at a magnification of 120 diameters (figs. 5 to 14). 
II. A Snort ACCOUNT OF THE LEMUR AND CORRELATION OF ITS MODE OF 
LIFE AND HABITS WITH THE CORTICAL DEVELOPMENT OF THE BRAIN. 
The true lemurs are found only in Madagascar, and frequent the forest in 
large numbers. Small, agile animals, hardly the size of a cat, with fox-like 
faces, large ears, long tails, and thick fur, they are eminently adapted to an 
arboreal life. They are able to run along the branches with great rapidity, 
using all four limbs, but they also spring from branch to branch with ease. 
The thumb and great toe are opposable, a feature which is not found in 
lower mammals, but which is characteristic in the primates. At the same 
time they seem to prefer to seize their food with their mouths, and do not 
grasp with the fore limb so readily as the apes. Though active and playful 
and fairly easily tamed, these animals, as compared with the monkeys and 
apes, are not very intelligent. Their food consists of fruit, nuts, and also 
insects and birds’ eggs. They are nocturnal or diurnal, and are probably 
guided in their search for food to a large extent by their sense of smell. 
The olfactory region of the brain, with the olfactory tracts and bulbs, is 
extremely well developed, and very much larger and more extensive 
proportionately than that of the primates. The large ears and well- 
developed semicircular canals may be correlated with the comparatively 
large temporal lobe and an acuteness of hearing obviously useful to a 
nocturnal feeding animal. The eyes, which are large, are set wide apart, 
so that the visual axes cannot be parallel; consequently, the animal does 
not, like the ape, possess convergent binocular stereoscopic vision. This fact 
finds anatomical expression in lack of macula, relatively smaller optic nerves, 
_ and absence in the brain of a definite occipital lobe. 
