TABLE 10 



This table deals, in its right and left halves, with the same material as the corre- 

 sponding parts of the preceding table; but in the present instance each boundary 

 and associated half of a regenerating zone is considered separately. On the left 

 side of the table are summarized the facts represented in tables 3 to 6 in so far as 

 these concern the character of the spaces through which the planes of division 

 pass. The symbols in the column headed 'B' are the same as those in the columns 

 of bounding mesenteries in those tables and have the same significance. In the 

 column headed 'Frequency' are given the number of instances of the hounding 

 mesenteries indicated on the left recorded in tables S to 6, and the sum of these 

 frequencies is the total number uf symbols in the columns of bounding mesenteries 

 in those tables. Since each old bounding mesentery is separately considered 

 here, the sum of the numbers in the column headed 'Frequency' is twice the sum 

 of the numbers found in the corresponding column of table 9. 



Omitting doubtfully complete endocoels, doubtfully incomplete endocoels, and the 

 four examples indicated in the last row, we find the ratios and percentages of 

 locations of the fission planes to be as follows: complete endocoels, 103 (62 per 

 cent): incomplete endocoels, 57 {34- per cent): exocoels, 6 (4 per cent). The ratio 

 of complete to incomplete endocoels, is 103: 57, or 64- per cent to 36 per cent. 



On the right are given the frequencies of the numbers of complete mesenteries (at the 

 heads of the columns) regenerated between the new directive plane and the hounding 

 mesentery indicated at the left of the rows. This part of the table includes speci- 

 mens from table 7 in addition to those of tables 3 to 6. Of necessity, it excludes 

 such specimens as did not clearly show the final number of regenerated mesenteries. 

 Because of these inclusions and exclusions the number of individuals repre- 

 sented in the two halves of this table are not the same. The total number of re- 

 generated mesenteries represented in this table is the same as in table 9. 



The average number of mesenteries added in the course of a division followed by 

 regeneration may be obtained as follows: take the average number of mesenteries 

 indicated in each horizontal row of the right half of the table {omitting doubtful 

 rows) and multiply by the frequencies given on the left; add these totals and divide 

 by the sum of the frequencies (omitting doubtful ones). This gives ^.2 as the 

 average addition for a lateral half of a regenerating zone, or 8.4- per regenerating 

 area. 



Note. The four cases, in the last row, designated by a dagger refer to no. 18b and 

 no. 22b, table 5, in which specimens two successive fission planes have apparently 

 cut away first one and then a second old bounding mesentery. (For fuller ex- 

 planation see p. 189.) 



POSITION OF DIVISION PLANE 



f Non-directive 

 Directive 

 Doubtfully complete. 



Endocoels 



Incomplete . < 



First grade 



Second grade 



Third grade 



Undeterminable grade... 

 Doubtfully incomplete. . 



Exocoels . 



(See note). 



c 

 d 

 c? 



(I) 

 (11) 

 (HI) 



(1) 



(D? 



FRE- 

 QUENCY 



97 

 6 

 1 



42 

 8 

 4 

 3 

 3 



COMPLETE 

 MESENTERIES 

 REGENERATED 



2 3 4 5 6 



24 



93 



2 1 



241 



