CELL 
SIZE AND 
TABLE 9 
NUCLEAR SIZE 
39 
Rate of nuclear growth during the cleavage of Crepidula plana 
MAXIMUM |COEFFICIENT) MEAN  (|COEFFICIENT| MINIMUM |COEFFICIENT 
STAGE BLASTOMERES | NUCLEAR or NUCLEAR OF NUCLEAR Or 
VOLUMES | GROWTH | VOLUMES | GROWTH | VOLUMES | GROWTH 
cubic cubic wu cubic 
Z)cellanwAB CD sscdnecseeiye 14,476 1.0 6,110 1.0 381 1.0 
Sicelisy Ay By CD asoocr tees 23,100 1.6 8,580 1.4 602.4 1.58 
cate 10.513 DSaaeanioecnoeees 19,396 7,068 338.4 
Va—Udlet/ischesaeics adapecee 5,748 3 620 338.4 
25,144 1.738 10.688 1.74 676.8 WaT 
DAH ID Seve eyaclene 12,220 7,068 338.4 
16 Galle DADs Mee eons 7,068 3,620 338.4 
Senate Tee nen eee 3,620 1,528 235.2 
1 Vo LD re ee 720 452 235.2 
23,628 1.63 12,668 2.07 1147.2 3.01 
GASB ID) re ectemeielsosss 8,580 5,748 150.0 
DAO casa et tess eats 5,748 3,620 150.0 
24 cell Pal diss she aenataeree 5,748 3,620 150.0 
GH De oa lec 5,748 3,620 150.0 
NEVES Kc BRS eet ae 3,620 1,528 235.2 
Laz ld2a sss. sere 720 452 235.2 
30,164 2.08 18,588 3.04 1070.4 2.80 
UNE DY. aa ons soo 12,220* 7,068 171.3 
0 ee a Ee 697 382 58.8 
AAC OGER wept th aati 2,715 1,146 112.5 
Sa Sd aera 5,748 3,620 150.0 
32 cells 4 2al—2d!. 1... eee ee 5,748 3,620 150.0 
Data De ia cinco 5,748 3,620 150.0 
IW Ne Le aaadoe 3,620 452 150.0 
Pat 2 Vdh.2 eis actcis 3 2,095 3,620 150.0 
IGE 0 Cae anne 720 452 235.2 
39,311 2.71 23,980 3.92 1327.8 3.48 
Total growth in thirty divi- 
SIONS Sas star atoyeycyar oie. ejace ies ie eiatels 24,835 LS 17,870 3.92 946.8 3.48 
Average growth for each divi- ; 
SUM Ear Teyersiss ciate sersiatelatererecs 827.8 1.05(=5%)| 595.6 1.09(=9%) Bile) 1.08(= 8%) 
* This volume is reached only at a much later stage, shortly before the closure 
of the blastopore (fig. 6). 
During this same period from the 2-cell to the 32-cell stage the coefficient of 
growth of maximum nuclear surfaces is 4.28, or an average increase of about 11 
per cent for each division. 
