Independent Development of the Lens. 397 
absent. These results are given in full in another paper. The 
solutions employed act as anesthetics preventing the usual out- 
pushing of the optic vesicles from the brain to a greater or less 
degree, and give exactly the same condition so far as contact 
influence of the optic vesicle on the lens is concerned, as though 
the optic vesicle was cut away, without the disadvantages 
accompanying the operation. 
The experiments with anesthetics furnish a richness of material, 
hundreds of specimens being obtained, which one would be unable 
to duplicate from operations without spending days of tedious 
labor. The crystalline lenses may be seen with the binocular 
microscope as spherical refractive bodies in the living specimens. 
The experimenter in this way is enabled to select various condi- 
tion for study. 
The embryos were best preserved for histological study in 
picro-acetic though many fixitives gave good results. The lenses 
stain equally well in eosin or picric acid used as a counter stain 
after Mann’s hematein or Delafield’s heematoxylin. 
3 THE LENS IN LIVING EMBRYOS 
The living embryos at various stages when examined with a 
binocular microscope show lenses isolated entirely from the optic 
vesicle or optic cup. Figure 1 illustrates an embryo eighteen 
days old that has no trace whatever of optic cups yet two per- 
fectly developed transparent lenses occupy almost normal posi- 
tions on the sides of the head. Sections of this specimen show the 
two lenses with well differentiated fibers, fig. 5 and plate II, 
fig. 3. _Mesenchymatous tissue lies between the lenses and the 
brain. We must conclude that these lenses arose in lateral 
positions and continued development and differentiation with no 
direct influence whatever from either optic vesicle or the brain 
tissue. The possibility of optic cups having arisen and degener- 
ated is entirely out of the question, since, in the first place, this 
has never been known to occur in any of the hundreds of Fundulus 
embryos that the writer has studied. In the second place, plate I, 
fig. 1, shows a lens arising from ectoderm on the eyeless side of 
