380 Charles R. Stockard. 
outward to meet the ectoderm as the writer (09) has supposed. 
Considering the case of the single eye it might be held that the fail- 
ure of certain central tissues of the brain to develop would cause 
the eye to arise too near the median line, but this lack of central 
tissue does not explain why the eye faces the median plane instead 
of the lateral head wall, and it is much less able to account for the 
absence of the eye on the opposite side of the head. On the other 
hand, if the conditions are due to a lack of the necessary develop- 
mental energy or an anesthesia produced by the experiment, then 
itis evident that although one eye does succeed in pushing out from 
the brain it might not have sufficient developmental energy to grow 
dorsally and outward to the lateral body wall, but droops, as 
it were, into a more ventro-median position and faces in toward 
the median plane. Thus one-half of an incomplete eyclopean 
eye is formed. The other eye was entirely suppressed, lacking 
the energy- necessary to push itself out from the brain. This 
inequality in the developmental powers of the two eyes is indi- 
cated by their frequent asymmetrical condition. 
The two eye components do not always face the median plane 
and in such cases the eyes merely fail to grow out laterally. They 
come off ventrally from the brain and either face in a ventral 
direction or grow so as to face outward. 
The experiments fail to give any definite clue as to where the 
optic anlagen are located in the brain before they become visible, 
although Lewis’ operations on the embryonic shields of older 
embryos would seem to indicate that at that time the anlagen 
occupied somewhat lateral positions. 
It is clear from the foregoing consideration that aleohol has 
the power to induce the same typical ophthalmic defects that were 
formerly described in the embryos from the Mg solutions. The 
property common to both Mg and alcohol is their anesthetic 
effect on animals. The writer concludes that cyclopia, mon- 
ophthalmicum asymmetricum and entire absence of eyes, all of 
which are more or less arrested or inhibited condition of develop- 
ment, result from anesthesia during certain embryonic stages. 
Of course this may not be the sole cause of such defects; on the 
contrary the fact that they are produced in this way would indicate 
