HOMOTYPOSIS IK THE VEGETABLE KINGDOM. 
331 
(18.) B. Somersetshire Ceterach (Ceterach oliicinarum).—Some time after I had 
tried in vain to count any characters in Ijracken, I had a letter from Miss Agnes Fry 
saying that she thought it just i)ossihle that the lobes on the fronds of ceterach 
might be counted. The chief diliiculty, ol course, "was the indefinite character of 
the lobes near the tip—a difficulty which liad rendered the lobes in liracken 
impossible. The rather indefinite tip is here of greater consequence than in the 
hartstongiie or the chestnut leaf, for the total number of lobes is comparatively 
small. In some samples Miss Fry sent me, however, I agreed fairly closely with her 
estimates, and although the tip must form a difficiilty,"^' we settled that an attempt 
should be made to include ceterach in the present series. Miss Fry accordingly 
counted 9 to 11 fronds on each of 99 plants. It was necessary to take plants of 
very diflerent ages, and even if ceterach lie not so sensible to its environment as 
hartstongiie, it is quite possilile that part of the correlation oliserved is due to 
similarity of age. The absolute agreement of the result obtained with that for 
hartstongiie is one of the most striking things in the whole collection of data. 
Considering the difficulty of the tip in ceterach and the sensibility of the sori of 
hartstongue to environment, it may l^e a chance agreement, hut it is certainly one 
that gives ground for pause, and suggests further investigations of the degree of 
resemblance between like organs in ferns. The tabulation of the data and the calcu¬ 
lation of the constants are again due to Dr. Lee. 
Ceterach. 
Number of 
Mean No. of 
lobes. 
S. D. 
Coeffi¬ 
cient of 
variation 
S. D. of 
array. 
Per¬ 
centage 
variation. 
Correlation. 
Plants. 
F ronds. Pairs. 
99 
999 9098 
•2.3T677 ±-0902 
4-2278 ±-0638 
18-2485 
3-2795 
77-57 
■6311[± -0128] 
The distribution of frequency of the fronds is almost the same as that of the pairs, 
since the attempt was made to take 10 fronds; actually 80 plants had 10, 14 had 
11, and 5 only 9 fronds. 
Frequency from Pairs. 
No. of lobes . 
13. 
14. 
15. 
1 
16. 
17. 
18. 
19. 
20. ' 
i 
21. 
22. 
23. 
24. 
Frequency . 
55 
73 
146 
229 
375 
418 
584 
575 ' 
811 
726 
800 
805 
No. of lobes . 
25. 
26. 
27. 
28. 
29. 
30. 
31. 
32. 
33. 
34. 
35. 
36. 
37. 
38. 
1 
39. ‘ 
i 
Total. 
Frequency . 
1 
863 
679 
668 
386 
288 
215 
184 
91 
37 
45 
27 
0 
9 
0 
9 , 
1 
9098 
* Miss Fuy writes : “ It is very difficult to keep to a standard of counting for the tip, but I have tried 
to do so.” 
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