572 



CELL DIVISION IN EGGS OF CREPIDULA. 



No 



804 



805 



806 



807 



808 



809 



810 



811 



813 



\. 



814 



815 



816 

 821 



822 



823 



824 





X. Effects of Hypertonic Sea Water 



1. NaCl Added to Sea Water. 



Stage. 



Per 

 Cent. 



1-4 cells. 



1-4 cells. 



1-4 cells. 



1-4 cells. 



1-2 cells. 



1-2 cells. 



1-4 cells. 



1-2 cells. 



1-20 cells. 



1-20 cells. 



1-20 cells. 



1-20 cells. 

 1-2 cells. 



1-2 cells. 



1-2 cells. 



1 



2 



1-2 cells. 



3 



4 



1 



2 



3 



4 



1 



2 



3 



4 

 1 



2 



3 



4 





Time in 



Solution. 



4 hrs 



4 hrs 



4 hrs. 



4 hrs 



15£ hrs 



15Jhrs 



15* hrs 



15£hrs 



lhr. 



lhr. 



lhr. 



lhr. 

 16 hrs 



16 hrs. 



16 hrs. 



Normal S. W 



16 hrs 



Ohrs. 



Ohrs. 



Ohrs. 



Ohrs. 



Ohrs. 



Ohrs. 



Ohrs. 



Ohrs. 



17 hrs. 



17 hrs. 



17 hrs 



17 hrs 



8 hrs 



8 hrs 



8 hrs 



8 hrs 



Results. 



forms in connection with each germ 



form 



Figs 



tetrasters 



Chromatin clumped in center of nuclear vesicle; achro- 

 matin fills nuclear vesicle and in mitosis fills amphi- 

 aster; spindles shrunken and no fibers visible; 

 chromosomes scattered; cytasters, but no multipolar 

 spindles. Figs. 183, 189, 190. 



Chromatin clumped in nuclear vesicle; nuclei and 



spindles shrunk 



cytasters, but no multipol 



connective fibers form spindle, widest 



middle; achromatin as in preceding, divides ami- 

 totically; no plasma division. 



Chromatin not clumped, but forms a heavy reticu- 

 lum, or spireme; nuclei a little shrunken; cleavage 

 stopped. 



2-20 cells; yolk cleavage largely suppressed; nuclei 

 densely chromatic, not vesicular ; polyasters, kary o- 



meres. Figs. 195, 196. 

 Chromatin in dense masses; achromatin in numerous 

 separate vesicles, widely scattered, formed 



substance of spindles and rays; 

 cleavage. Figs. 184-188 



spindles 



Chromosomes do not form vesicles, but achromatin of 

 spindle and asters does as in Figs. 79-82 ; no cleavage. 



Figs. 178-182. . 



No cleavage; chromatin and achromatin separate and 

 distinct; chromosomes scattered; spindle of homo- 

 geneous achromatin, no fibers ; no radiations. 



8-20 cells; blastomeres abnormal in size and position; 

 in resting stage chromatin like spireme; sphere has 

 very definite outline, centrosomes dark and dense m 

 sphere ; mitoses few but distinct ; chromosomes do not 

 form vesicles, but achromatin and membrane form 



around them. ."._*. •+ •* 



8-25 cells, mostly normal ; abnormal only when mitosis 

 has been disturbed; no polyasters, some karyo- 

 meres; scattered chromosomes; chromatic connections 

 between daughter nuclei in few cases. Fig. ^ L , 

 8-25 cells; cleavage normal, development stopped 



mitoses normal ; no polyasters 



Similar 



25^0 cells; cleavage very irregular; yolk cleavage may 

 be smmressed or increased; polyasters and karyo- 



meres 



_ ; little cleavage and very irregular ; polyasters 

 and karyomeres. Figs. 174, 175, 177, ^J- 

 •2 cells; no cleavage, no asters, no ce^osomes o 

 spheres; nuclei may be enormous and chromatic o 

 small and clear; the latter, which were BijJJJ' 

 beginning of exp., have not taken in ^^ 

 which is scattered as homogeneously colored spner 



ules. 



big 



Figs. 171-173, 176, m, ^ 

 1-2 cells; similar to preceding; r 

 stricted and lobulated as in ami 

 astral rays contracted, spindle fibers iuseu, « 

 somes scattered; achromatic spherules wiae 

 tered. 



