The Formation of the Aster in Artificial Parthenogenesis

In normally fertilized eggs the development of the aster is attributed to a substance carried into the egg by the spermatozoon. The aster first makes its appearance in the form of diminutive radiations surrounding the neck-piece of the spermatozoon within a few minutes after it has entered the egg. The writer 1 has shown that the formation of the radiations is accompanied by a jellying of the cytoplasm of the egg. The jellying process extends more and more as the aster increases in size and the entire egg becomes involved when the center of the aster comes to occupy the center of the egg. .The formation of the aster is accompanied by an increase in size of a hyaline area in its center. This is Wilson's hyaloplasm-spherO also called centrosphere and astrosphere by other investigators. The microdissection method has demonstrated that this sphere area is liquid in contrast to the surrounding jellied cytoplasm. The pioneer observers of mitotic division, such as Auerbach, Hertwig, Biitschii and Fol, described the accumulation of a hyaline plasma at the astral centers and suggested that the astral radiations are a result of protoplasmic currents. Later investigators, such as Morgan, Wilson and Conklin, considered this view as the most probable one.