Warren Harmon Lewis 151 
strand in its neighborhood. Some of these ectodermal masses are quite 
irregular and branched, as in Figs. 52, 53, 54, 55, 56, 58, 60, and 62, 
the lens forming from only one portion of it. Such ectodermal masses 
may be attached to the ectoderm or pharynx or both. Sometimes the 
ectodermal process or mass is-free and the larger part of it developing 
into a lens under the influence of the optic cup, as in Figs. 61, 62, 63, 
G4, 66, 67, 68, and 69. The lenses forming from such masses often show 
retarded differentiation (compare Figs. 63 and 65). 
Very often there is between the ectoderm and the pharynx wall an 
ectodermal connection, and the lens may arise from it, as in Fig. 70. Al- 
though these processes may be attached to the pharynx wall, as in Figs. 
53, 54, 55, 58, 60, and 70, one can distinguish between the two tissues. 
There are a number of deeply transplanted eyes in contact with the 
pharynx and peritoneum, but these tissues do not seem to be able to give 
rise to the lens. The formation of a lens from ectoderm in the region 
of the otic vesicle has apparently no influence on the formation of an- 
other lens from the normal region of the same side of the head by the 
regenerating eye as occasionally both transplanted and regenerating eyes 
may show lens-formation from the ectoderm. This would seem to indi- 
cate that lens-formation is a purely local process. Nor is any connec- 
tion of the transplanted eye with the brain necessary for lens-formation, 
as in most cases no connection whatever exists between transplanted eye 
and brain. 
There is apparently no predetermined area of the ectoderm which must 
be stimulated in order that a lens may arise. As to whether there exists 
any polarity as regards the ease with which the ectoderm responds to the 
lens-forming stimulus can scarcely be determined from these experi- 
ments, as a much more complete series with eyes transplanted into 
various other regions would be necessary and even then it would be a 
difficult matter to determine if the normal lens-forming ectoderm was 
more readily acted upon than ectoderm farther caudal, as the difficulty 
of bringing the transplanted eye into as favorable relations with the 
ectoderm as in the normal region must be taken into consideration. 
As to whether the lens can arise from any other structure as the otic 
vesicle, the pharynx wall, the peritoneum, the brain, ete., through the 
influence of the eye is in no way indicated by my experiments and there 
are examples where the eyes have come into contact with these structures 
without any signs of lens-formation. 
For how long a period such transplanted eyes and lenses would con- 
tinue their normal development can only be determined by further 
experimentation. 
