484 ROBERT CHAMBERS, JR. 



astral radiations often persist about the poles of the spindle 

 being apparently dragged along with them (Spooner '11), F. R. 

 Lillie ('09), suggests that the aster about the poles of a dis- 

 located spindle is a new configuration, and due to forces (see 

 Hartog '05), which are focussed in the centrosomes and influence 

 the cytoplasmic granules in situ. A significant phenomenon is 

 the occasional occurrence of distortion of the astral rays not 

 only in centrifuged but also in normal eggs (Mark '81, Coe 

 '99, Conkhn '02, and Painter '16). Investigators generally 

 agree in considering the distortion to be a proof for the existence 

 of more or less extensive movement in cell protoplasm and some 

 conclude that the rays may be firmer in consistency than the 

 surrounding cytoplasm. 



In a recent paper Heilbrunn ('15) describes in the cytoplasm 

 of sea urchin eggs a gelatinization produced by chemical agents 

 which cause the eggs to undergo parthenogenetic development. 



While investigating the structures of various marine ova by 

 micro-dissection, the author found it possible to detect changes 

 in the consistency of the protoplasm during aster formation and 

 to demonstrate that during cell division we meet with definite 

 reversible gelation phenomena. 



2. Material and method 



The microdissection method, first introduced for the study of 

 protoplasmic structures by Kite (Kite and Chambers, '12), 

 affords means of collecting direct evidence of the physical con- 

 sistency of many constituents in the living cell. The apparatus 

 used for holding the dissection needle is the mechanical pipette- 

 holder of Barber. A detailed description of the instrument and 

 of ways for making the micro pipettes and needles is given by 

 Barber in his paper ('14). An elaboration of the method for 

 microdissection purposes is being published (Chambers, '17). 

 A preliminary description has been given (Chambers, '15). 



The needle is drawn out of hard glass tubing. It is 

 manipulated with Barber's instrument and projects into a 

 moist chamber on the stage of the microscope. The tip of the 



