Now we come to the last and the most important series of morphological phenomena that should be attributed to the direct influence of external nature and its forces These phenomena are before us in the study of the different stages development of embryos of Metazoa in their common type. We restrict ourselves to the already indicated fact that the first contrast between the peripheral and the Central part is detected after the number spontaneous divisions turned the original fertilized stem cells a group of cells that make up pochacco or primitive germ. Where the interior mass is insignificant, as, for example, in lower animals, do not lay considerable supplies of food, together with the beginnings of their offspring, the outer layer of cells, which is quickly becoming absolutely small because of repeated division, forming the entire clothing the surface of the membrane, the blastoderm. The next stage of development leading to him doubling the covering layer is achieved in two ways - by invagination (the impression) and delamination (cleavage) which is original path, and which is simplified, is not yet fully elucidated. About intussusception, numerous examples which represent the most inferior types, Balfour says: "On purely a priori grounds my belief leans toward the recognition of the theory of intussusception, preferably before any other point vision" {"A Treatise on Comparative Embryology, by Francis M. Balfour" LLD Vol. II, p. 343 (second edition).}; for our purposes, can be satisfied this recognition and understanding of the nature of the process, the reader-the layman through a simple illustration.
Now we come to the last and the most important series of morphological
ReplyDeletephenomena that should be attributed to the direct influence of external nature and its
forces These phenomena are before us in the study of the different stages
development of embryos of Metazoa in their common type.
We restrict ourselves to the already indicated fact that the first contrast between
the peripheral and the Central part is detected after the number
spontaneous divisions turned the original fertilized
stem cells a group of cells that make up pochacco or
primitive germ. Where the interior mass is insignificant, as, for example,
in lower animals, do not lay considerable supplies of food, together with
the beginnings of their offspring, the outer layer of cells, which is quickly becoming
absolutely small because of repeated division, forming the entire clothing
the surface of the membrane, the blastoderm. The next stage of development leading to
him doubling the covering layer is achieved in two ways - by invagination
(the impression) and delamination (cleavage) which is
original path, and which is simplified, is not yet fully elucidated. About
intussusception, numerous examples which represent the most inferior types,
Balfour says: "On purely a priori grounds my belief leans toward
the recognition of the theory of intussusception, preferably before any other point
vision" {"A Treatise on Comparative Embryology, by Francis M. Balfour" LLD
Vol. II, p. 343 (second edition).}; for our purposes, can be satisfied
this recognition and understanding of the nature of the process, the reader-the layman
through a simple illustration.