148 Lens-Formation from Strange Ectoderm 
which would have soon disappeared. A section through the center of 
this lens-bud, as seen in Fig. 11, shows quite clearly the lens-like nature 
of the structure, but it is not as far differentiated as the normal one 
(compare with Fig. 13). 
Figs. 14 and 15 show another large lens-bud associated with a trans- 
planted eye. This lens-bud has quite a long pedicle, as seen in Fig. 15, 
Fig. 17 shows a very normal appearing transplanted eye with a lens 
vesicle which has evidently just broken away from the ectoderm, as 
shown in Fig. 16. This transplanted eye is about the shape of the nor- 
mal but the lens is not as far advanced in its differentiation (compare 
with Fig. 18). Fig. 19 shows another lens-bud associated with an eye 
transplanted ventral to the otic vesicle. The lens-bud has evidently just 
broken away from the ectoderm. Its size and shape are better seen in 
Fig. 20. It is not as far differentiated as the normal one shown in Fig. 
21. Figs. 22, 238, and 24 show another lens-bud which has just separated 
from the inner layer of the ectoderm, probably by an artificial break. 
The transplanted eye hes ventro-mesial to the otic vesicle (see Fig. 23). 
The embryos in the above experiments were killed from 3 to 34 days 
after the transplantation of the optic vesicle and they all show unmis- 
takable evidence of the origin of the Jens from strange ectoderm. This 
is seen occasionally even in embryos killed 4 days after the operation, as 
in Fig. 25, where one end of the lens vesicle projects towards a projection 
on the ectoderm. This was rather of an irregular lens vesicle, as seen 
in Figs. 26 and 27. 
The lens in some of the embryos killed 3 days after the operation may * 
show no signs of its origin, as in Figs. 28 and 29, although the ectoderm 
may, as in Fig. 29. In others, as in Figs. 30 and 31, neither lens nor 
ectoderm show signs of the origin of the lens, though these embryos were 
killed only 3 days after the transplantation of the eye. In almost all 
of these embryos killed 4 days after transplantation of the optic vesicle 
the transplanted eye and its lens are separated from the ectoderm by 
mesenchyme, as seen in Figs. 32, 33, 35, and 37, and there is no trace 
of any connection between the lens and ectoderm, except, perhaps, in 
Fig. 35. The lenses in these experiments are not as far advanced as the 
normal one (compare with Fig. 36). 
In the embryos killed 5 days after the transplantation (see Figs. 34, 
38, 39, and 40) there is no indication of the origin of the lens, likewise, 
in those killed 54 days after the operation (see Figs. 41 and 42). The 
transplanted eyes in the older embryos are as a rule separated by a 
greater thickness of mesenchyme from the ectoderm, and both the optic 
