CELL SIZE AND NUCLEAR SIZE 41 
TABLE i0 
Actual nuclear diameters and volumes in the 70-cell stage of Crepidula plana 
NUCLEAR |TOTAL NUCLE comment ia ORE 
een cea pak te | VOCUME | Nuclear Nuclear 
| | volume | surfaces 
| a Ml | 
DICE list ae Gremmr te teehee na ratte e sie lbeen 4: 14,476 | 1 1 
(AAR re ea eho 16 8,579 
BAC eee eh og 10 1,571 
11 Entomeres E!, E2 ; 7 359 
RetRezamees Ales oh se ur ae od 2260 
4 Mesomeres fae os CO te x | eee | | 
First quartet | | 
4 Apicals; lat oldu, say oe ls. HOM») 2525004 
3 Basals, lal-?-1-1e2-21, aa allay, | 
1 Basal, Hae tao, & a a 905 | 
| 3 Middles, la!:2:2-1el-2-2,.......... 12 | 2,714 | 
APAvurnetslia2—ld2 05 sae ee ee 7 718 | 
Second quartet | | 
-- Selupicellsh Zatti 2el La ane 6 | 339 
Or aempcelll: PL NE ass ce MR i 10 524 
4 4 Girdle cells, 2a!-2-1-2d!:2-1,.. 11... 9 1527 
S |4 Girdle cells, 2a!-2-2-2d!-2-2,,......| 10 2,094 
f] |4 Girdle cells, 2a2-1--2d2-1-1,.00 0... 9 1,527 
as) 4;Girdlecells\2a2 = 2 2d7-125. 9 1,527 | 
4 Girdle'cells; 2a?:2-2d?*2,.......... 5 | 262 
Third quartet | | 
4 Girdle cells, $a!--3dt-).. 20... 10 | 2,094 
4 Girdle cells, 3a!:2-3d!2 .......... 9 1,527 
4. Girdle'cells; 3a?-—302-)5.. 1.22... 6 | 452 
(4 Girdle cells, 3a2-?-3d2-2........... 6 452 
70 cells. Total nuclear volume........ | 32,446 2.24 5.30 
The total volume of these 70 nuclei is almost exactly the same as the volume 
of the germinal vesicle, about 50 per cent more than the volume of the germ nu- 
clei, and 35 per cent more than the mean nuclear volume of the 32-cell stage, with 
which mean volume, rather than with the maximum, this actual volume of the 
nuclei of the 70-cell stage should be compared. In the 88 nuclear divisions lead- 
ing from the 32-cell stage to the 70-cell stage the nuclear material has increased 
at an average rate of less than 1 per cent for each division. 
