1920] 



S EI FRIZ— PRO TOP LA SM 



S79 



The rays of the amphiasters, like the two polar spheres, are 

 apparently also of dilute protoplasm. This thin hyaline sub- 

 stance which makes up the astral rays and polar areas is of liquid 

 consistency (v. v. 3). Although quite dilute it is not watery. In 

 connection with the low viscosity of the hyaline rays it is interest- 

 ing to recall the theories which have been advanced pertaining to 

 the flow of the substance of which the rays are composed. Auer- 

 bach was probably the first to advance the theory that the rays 

 were currents of a protoplasmic substance. Others, notably Fol, 

 have advocated a similar theory. Wilson (28) likewise upholds 

 this theory with the statement that "no one .... can, I think, 

 doubt that such a centripetal movement occurs, or that the clear 

 hyaloplasm flows inwards to form the growing hyaloplasm-spheres." 

 Strasburger (24) states that he, with Fol, looks upon the astral 

 rays as "centripetal currents," to which Strasburger ascribes 

 the function of "carrying to the astral body substance which 

 serves as nourishment for the new nucleus." 



The protoplasm peripherally located, and also that making up 

 the wedge-shaped protrusions which alternate with the hyaline 

 rays and thus give to the mitotic figure its starlike appearance, is 

 all of high consistency, being very or extremely viscous (v. v. 7 or 8). 



A very convincing demonstration of the fluidity of the sub- 

 stance of which the astral spheres and rays are composed was 

 obtained through dissection and 



previous vital staining with 



neutral red. The eggs were placed in a very weak stain of neutral 

 red at the time they were fertilized, and allowed to lemain in the 

 stain during division, which requires about an hour. The clear 

 liquid substance of the spheres and rays stains a brilliant pink, 

 while the surrounding highly viscous granular plasma takes on 

 little if any stain. A stained ovum in the early anaphase of 

 mitosis was torn until a small globule of protoplasm adjoining the 

 egg had been formed. By pressure against the egg the protoplasm 

 from it could be forced into the globule, thus enlarging the latter, 

 and then by pressure against the globule the protoplasm could be 

 forced back into the egg. The protoplasm which could thus 

 again and again be made to flow from the egg into the globule, and 

 vice versa, was the stained hyaline liquid substance of the astral 





