STUDIES WITH THE CENTRIFUGE 45 



The fibers of the spindle are as distinct as they are in the normal 

 egg and there is no sign of tearing. The chromosomes are not 

 displaced and the asters occupy their normal positions at the end 

 of the spindle. The astral rays pass out into the surrounding 

 protoplasm and there is no sign of modification of their perfectly 

 radial arrangement. This is the strongest evidence against the 

 theory that they are true fibers. A radial system of fibers could 

 hardly be supposed to remain undistorted after being pushed 

 through the egg. 



The spindle was centrifuged in all stages, even as late as the 

 time when the chromosomal vesicles are forming. The result 

 was always the same. The nuclear elements lie under the oil 

 cap. Eggs killed ten to fifteen minutes after centrifuging show 

 that in that time there is no return of the spindle toward the 

 center of the egg. 



BIBLIOGRAPHY 



BovERi, Th., and Hogue, M. J. 1909 Ueber die Moglichkeit Ascariseier zur 

 Teilung in zwei gleichwertige Blastomeren zu veranlassen. Sitz.- 

 Ber. d. Phys. med. Ges. Wiirzburg. Jahrg. 1909. 



LiLLiE, F. R. 1909a Polarity and bilaterality of the annelid egg. Experiments 

 with the centrifuged egg. Biol. Bull., vol. 16. 



1909b Karyokinetic figures of centrifuged egg; an experimental 

 test of the center of force hypothesis. Biol. Bull., vol., 17. 



Lyon, E. P. 1907 Results of centrifuging eggs. Arch. Entwickelungsmech., 

 Bd. 23. 



McClendon, J. F. 1909a Cytological and chemical studies of centrifuged frog's 

 eggs. Arch. Entwickelungsmech., Bd. 27. 



1909b Chemical studies on the effects of centrifugal force on the eggs 

 of the sea urchin (Arbacia punctulata). Am. J. Phys., vol. 23. 



Morgan, T. H. and Lyon, E. P. 1907 The relation of the substances of the 

 egg, separated by a strong centrifugal force, to the location of the 

 embryo. Arch. Entwickelungsmech., Bd. 24. 



Morgan, T. H. and Spooner, G. B. 1909 The polarity of the centrifuged egg. 

 Arch. Entwickelungsmech., vol. 28. 



