1406 
This eyclopian brain therefore is arhinencephalie only in its 
frontal part, not in its temporal part. The necessity of the frontal 
arhinencephalia is sufficiently illustrated by the scheme in fig. 1 
and fig. 2. 
It also illustrates, that the eyestalks and eyevesicles lying much 
more laterally remain aninjured by the defect or if they are touched 
Fig. 3. The dorsal face «of a human Fig. 4. Ventral face of the brain of the 
cyclopian brain (diophthalmos monorbi- same cyclopian being. 
taris). f.b.m. = fissura baso-medialis. G. olf. post. = 
a. Brain-matter. b. roof of the 3rd ven- gyrus olfactorius posterior. 1N.S= Insula Reilii. 
tricle. c. adhaesion to the dura mater. d. N. II. = Nervus opticus. N.//I, =Nervus ocu- 
entrance to the cavity of the sac. lomotorius. ¢. 7. = corpus mammillare. 
by it, are only destroyed in the midline, in their mesial parts. The 
eyes are placed close together or eventually unite. 
The praechordal layers, lying ventrally from the brain vesicle, do 
not develop. Consequently the matter, destroyed by the burst which 
in a later stage is going to form the tissue, found between the os 
sphenoïdale and the os frontale, will be missing and the orbits will 
appear close together or united into one. In this way the total range 
from the arhinencephalic cebocephalia to the complete cyclopia is 
also understood, 5 
However it is obvious, that the extension as well as the place of 
the medio-basal frontal burst and probably also the period in which 
it occurs, can vary between certain limits. 
First its extension. A very small, strictly medially lying bursts 
will always cause frontal arhinencephalia, but the loss in the 
midline of the future praechordal basal skuli-elements are more or 
less independent of the extension of the brain defect. It may be 
