

562 



CELL DIVISION IN EGGS OF CREPIDULA 



No. 



910 



911 



912 



913 



914 



915 



916 



917 



918 



919 



III. Effects of Pressure.— (Continued.) 



Stage. 



Experiment. 



Free 



Duration. | in Sea 



Water. 



Results 



4-20 



cell 



Pressed 



capsul 

 Pressed 



out of 4 hre. 



• I 



out of 4 hre 



4-16 cells 

 1 cell. 



capsules. 



Pressed in cap- 

 sules. 



Pressed in cap- 

 sules. 



4 hrs. 4-24 cells; many isolated macromeres. 

 4 hrs. 1-8 macromeres, which are abnormal in 



size 



and 



4 hre. 4 hrs. 24-30 cells ; normal 



Figs. 51, 52, 53 



4 hre 



4-16 cells. [Pressed in cap- 

 sules. 

 1 cell. iPressed in cap- 

 sules. 



4 hre 



4 hre 





1-16 cells; cleavage of yolk suppressed in 

 some eggs, increased in others (1-many 

 macromeres), depending on axis of pressure. 



4 hrs 



6 hrs. 24-30 cells; few modifications 



6 hre 



4-8 



4r-16 



Pressed out of 



capsules. 

 Pressed in cap- 



1 cell. 



920 

 ,000 (1) 



(2) 



sules. 

 Pressed 



out of 



capsules 



cell. Pre»ed out of 



4 hre, 

 4 hre. 

 4 hre 



6 hre 





6 hre 



6 hrs 



1-8 macromeres with corresponding micro- 

 meres; many exovates and lobes; amitosis- 

 like division figures. Figs. 54, 56, 59, 60, 



61,65. , 



4-24 cells; a few exovates and isolated macro- 

 meres. 

 24-30 cells ; nearly normal. 



20 cells : many modifications in number 



1 



cells. IPre 



capsules 



out of 



1 



,psul 



cells. | Compressorium 



4 hre 

 4 hre 



and position 



Figs 



o 



Fig 



1-2 cells. Compresso 



(3) 1-2 cells. Compressorium 

 ,001 (1) 1-2 cells. Compressorium 



16 hre. 

 16 hre 





16 hre 



(2) 

 (3) 



.002 



cells. Compressorium 

 cells. ; Compressorium 



15 hre. hre. 1 



6 hre. Similar to preceding. 

 6 hre. 8-24 cells; similar to 



hre. 116-25 cells; more than 4 macromeres with 



corr 



6 hre. 116-30 , _ 



than 4 macromeres. Jbig. W. , 



52-70 cells: some isolated macromeres, showing 

 artial cleavage. Fig. 67. 



cells; many isolated macromeres, also 



exovates. Fig. 



ding micromeres. Fig 



a few eggs with exovates and 



16 hre. 



15 hre 

 15 hrs 



(2) 



003 



.004 



cells. IPressed between! 6i hre 



slides. 



Pressed between 5 J hre. 



hrs. 

 hre. 



hrs. 



cells 



1-4 



(2) 



cells 



slides. 



Pressed between 

 slides. 



Compres8ori um 



1-2 cells. Compressorium 



7 hre. 



7 hi* 



hrs. 



7*hri 

 7* hre 



hre 

 7 hrs 



eggs with 1-8 macromeres ; exovaw». 



66. 



1-42 cells; similar to preceding. 



52-70 cells; a few with more than 4 macro- 

 meres. Figs. 67, 76. timber 



1-8 cells; macromeres abnormal in number, 

 sise, and position; exovate and isolated 



| macromeres. tk- 19 



8-25 cells ; similar to preceding, Jug- «• 



2-16 cells: macromeres abnormal jn number, 

 Biie and! position; isolated macromeres and 



and exovates. Figs. 57, 58. 



similar to preceding. 



8-40 cells; similar to No. 1,002. 



