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insignificant or large. On its extension, it will deperd what place 
the future monstrum occupies in the range between arhinencephalia 
and eyclopia. 
Still of greater importance is the location of the burst, and still 
more, the line of direction, in which the brain-vesicle ‘bursts. There 
exist some details in different evelopian monstra, which are not so 
well understood in accepting the other above mentioned interpretations, 
as they are by accepting that a primary lesion at the mesencephalic 
roof causes the burst in the base of brain. 
Ii makes some difference for the future morphologic development 
of the embryo whether the burst goes through the medio-ventral 
vesicle-wall a little farther or a little less far frontalwards, whether 
it lies precisely in the midline or somewhat laterally from it. It is 
not even unlikely, that place and direction of the burst are connected 
to a certain point with the time of termination. 
It is not necessary that the burst forces the medio-ventral wall of 
the vesicle exactly frontally from the place, where the chiasma is 
going to develop, even although the most frequently oecurring form 
of eyelopia is represented by the eyclopia ineompleta, in which, 
except the lamina terminalis, also the mediat half of the eye vesicle 
is destroyed, so that afterwards the eyestalks are found as two 
optic nerves on one fully developed eye, composed by two half 
eye-vesicles. 
If the burst is supposed to begin more distally, e.g. even foreing the 
place where afterwards the chiasma will appear and destroying at the 
same time the proximal part of the medial walls of one or both eyestalks ; 
then there is no reason why — given the tendency of development 
of isolated parts (the independent developed eyes of the anencephalus) 
— the two united eye-vesicles should not develop into one eye. 
In such cases the optic nerves mostly united into one nerve, ends 
blind, whereas there is not found a chiasma, nor even a mamillary 
body (e.g. in the case described by Davipson Brack). 
Probably it is also of great importance, how the relations of 
development are between the ventral wall of the brain vesicle and 
the layers located ventrally from it, which will produce the middle 
parts of the skull. 
From this point of view the brains of the two cyclopian calves 
seemed important to me. 
They principally did not differ from those of the eyelopian human 
beings, which I examined. But important is the difference of the 
details. 8 
In one, reproduced in fig. 5 and fig. 6 the sac (6) again is found 
