CYTOLOGICAL STUDIES OF CENTRIFUGED EGGS 
T. H. MORGAN 
Professor of Experimental Zoology, Columbia University 
ONE HUNDRED AND NINETEEN FIGURES 
EIGHT PLATES 
CONTEXTS 
1. Centrifiiging the egg of Cumingia 594 
The effect of centrifuging on development 595 
The localization of the visible substances of the egg 600 
The location of the visible materials of normal eggs, and the effect 
of centrifuging 602 
' Centrifuging eggs in the ovary 611 
General considerations 612 
The role of the visible substances in the egg as organ-forming 
materials 612 
The formation of the aster and its relation to the chromosomes. . . . 614 
The movements of the aster in the egg 616 
The bearing of the results on the phenomenon of cleavage 617 
2. Centrifuging the egg of Cerebratulus 619 
Orientation of the egg in the centrifuge 621 
The fate of the inclosed polar body 624 
Segmentation of the centrifuged eggs 626 
Influence of centrifuging on the karyokinetic figure 627 
The nature of the cytasters and spindle • 630 
The role of the astral system in cell-division 631 
The specific gravity of the spermatozoon 633 
Comparisons with the Chaetopterus egg 634 
Comparison with the frog's egg 636 
3. Centrifuging the egg of Hydatina 537 
4. Centrifuging the egg of the fish 639 
The orientation of the egg on the machine 640 
The effect of centrifuging the egg immediately after removal from 
the fish '. . \ 643 
The method by svhich the protoplasm is drawn into the blastodisc. . . . 648 
Is gravity a factor in the formation of the blastodisc? 650 
Abnormal embryos after centrifuging 650 
Bibliography 655 
Plates 656 
