According to Balfour, the original embryological changes imply that the "functions of the Central nervous system, which the original was performed entirely by the skin, gradually began to concentrate in the special part, gradually separated from the surface and finally become the highest, well defined body, a prisoner in subdermal (subcutaneous) tissues.. Embryological data proves that ganglion cells of the Central part of the nervous system originally occurred from the simple undifferentiated epithelial cells of the body surface" {Balfour I. S. Vol. 2, p 400-401.}. Maybe a few strikes us less, though still sufficient extent, the fact that the eyes also evolved from the skin area and not only the lens and all the surrounding part of the eye have a similar origin, but and "the perceiving part of the organs of the special senses, especially visual organs are often formed from the same part of the original epidermis is", which forms and the Central nervous system {Balfour,I. c.Vol.2,p.401.}. The same is true concerning the organs of smell and hearing. They also arise in the form of bags formed by sealing of epidermis, and as their parts are developing they are inside the nervous system, which, in turn, is of epidermal origin.
According to Balfour, the original embryological changes
ReplyDeleteimply that the "functions of the Central nervous system, which
the original was performed entirely by the skin, gradually began to concentrate
in the special part, gradually separated from the surface and finally
become the highest, well defined body, a prisoner in
subdermal (subcutaneous) tissues.. Embryological data proves that
ganglion cells of the Central part of the nervous system originally occurred
from the simple undifferentiated epithelial cells of the body surface"
{Balfour I. S. Vol. 2, p 400-401.}.
Maybe a few strikes us less, though still sufficient
extent, the fact that the eyes also evolved from the skin area and not only
the lens and all the surrounding part of the eye have a similar origin, but
and "the perceiving part of the organs of the special senses, especially visual
organs are often formed from the same part of the original epidermis is",
which forms and the Central nervous system {Balfour,I. c.Vol.2,p.401.}.
The same is true concerning the organs of smell and hearing. They also
arise in the form of bags formed by sealing of epidermis, and
as their parts are developing they are inside the nervous system,
which, in turn, is of epidermal origin.