BRAIN 53 
lamelle. On a vertically longitudinal, or “sagittal,” section, it has 
a beautiful tree-like appearance. From the walls of-the central 
cavity branch-like 
white medullary 
fibres spread out, 
surrounded by a 
layer of reddish 
ganglionic cells, fol- 
lowed by larger 
ganglia (Purkinje’s 
layer), and exter- 
nally covered by a 
grey mantle of 
smaller ganglionic 
cells. Such a thin 
section, especially 
when stained with 
carmine, forms a 
fascinating object 
for the microscope, 
and is easily made. 
The surface of 
the cerebral hemi- 
spheres in Birds 
exhibits no convol- 
utions or gyrations 
as in the higher 
Mammals. In the 
Ratitee and in many 
Passeres the surface 
is entirely smooth, 
but in Swimmers, 
N. 7 VENTRAL VIEW OF THE BRAIN OF A Goose. Twice natural size. 
Waders, Pigeons, : 
: (After A. Meckel.) 
Fowls, and Birds- I-XII, the twelve pairs of cranial nerves; Ch. Chiasma of the 
of-Prey, there is a optic nerves cut across; Fl. Flocculus; H. Hypophysis; L.o. 
very slight furrow Optic lobe; Lg. Laqueus; FS. Sylvian fissure ; Sp.J. First spinal 
which might be” 
compared with the Sylvian fissure. There is also very little grey 
substance in the surface layers of the hemispheres. Various attempts 
have been made, by Tiedemann,! Serres,” Leuret,? and Bumm,* to 
compare the weight of the whole brain with that of the body, or 
1 Anatomie und Naturgeschichte der Vogel. Heidelberg: 1810. 
Anatomie comparée du cerveau. Paris: 1824. 
Anatomie comparée du systéme nerveux. Paris: 1839-57. 
Das Grosshirn der Vogel. Zeitschr. fiir wissensch, Zool. xxxviii. (1883) 
pp. 430-466, tabb. xxiv.-xxyv. 
bo 
i 
