author's abstract of this paper issued 

 by the biboligraphic service august 6. 



MICRODISSECTION STUDIES 



II. THE CELL aster: A REVERSIBLE GELATION PHENOMENON* 



ROBERT CHAMBERS, JR. 



Cornell University Medical College, New York City 



ONE PLATE 



L INTRODUCTION 



1. Historical 



The periodic appearance and disappearance of the aster in the 

 cell, the very definite structure which it offers to the eye, and 

 its very evident relationship to cell division make it one of the 

 most striking phenomena in cell protoplasm. 



Any idea which one may advance regarding its structure is 

 necessarily based on a conception of the structure of protoplasm. 

 There can be, therefore, as many interpretations of the astral 

 structure as there are theories of the physical make-up of pro- 

 toplasm. Taking for a basis the reticular theory of protoplasm, 

 the astral rays have been considered fibrous strands whose 

 radiate arrangement is produced by being drawn together at a 

 point in the protoplasmic fibrous network. In accordance with 

 Biitschli's foam theory of protoplasm the aster has been explained 

 as an arrangement of the protoplasmic alveoli into more or less 

 definite rows radiating from a common center. 



The experimental work of Morgan ('08, '10), Lilhe ('09), 

 Conklin ('12), and others on the centrifuged eggs has shown 

 conclusively that whatever be the structure of protoplasm the 

 mitotic spindle at least is of such a consistency that it preserves 

 its structure on being driven through the cell substance. The 



1 This paper was read before the American Society of Zoologists, New York 

 City, December 27, 1916. It is based on the work done during the summer of 

 1916. The writer wishes to express his indebtedness to Prof. H. V. Neal, for 

 accommodation and facilities accorded him at the South Harpswell Laboratory. 



483 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 23, NO. 3 

 AUGUST, 1917 



