1404 
The medio-ventral part of the frontal brain-pole is destroyed, the 
wounded medial faces of the frontal brain matter pressed against each 
other grow together, and in a later period of development, there is 
found no trace of their union, as is also the case in the embryo of 
fuhdulus, operated by Lewis. The germ-material destroyed by the 
burst is the cause of a brain-defect. Its result is a brain, arhinen- 
cephalic in its frontal part. 
The germ material lying beneath it, the future praechordal elements 
for the skull, is also destroyed. Their loss appears as a defect between 
the frontal and the sphenoid bone, which can always be demon- 
strated (if the skull must be spared, the X-ray foto of the skull 
may be necessary in men, in animals it is often directly seen). 
To illustrate this view of the origin of the cyclopian brain it is not 
necessary to go back to the early period, in which the cyelopia 
probably begins. 
Fig. J. Scheme of the brain of a human foetus of 5—6 
months old. The rhinencephalon is striped. The thick dotted 
lines roughly form the border of the baso-medial brain matter; 
which is lost by the embryonal defect. 
It may be supposed e.g. that there was cut out of the brain a 
part of the frontal base and in the midline, which is bordered 
distally by the chiasma, laterally by the limen insulae (the thick 
lines in fig. 1). 
