The Causes of the Zoning of Brown Seaweeds. 57 
(c). Errors due to insufficient stirring and variation in size of 
drops in the measurement of the dehiscence of the male conceptacles. 
Besides these a still more important source of error was found 
to he the variation in ripeness of the individual specimens, however 
carefully they were chosen. The only possible method of getting 
over this was to take a number of readings with different specimens 
for each experiment, and use only the mean value. The number of 
readings taken was, however, not sufficient to prevent this source 
of error from being a serious one. 
The results of a series of experiments carried out to ascertain 
the effect of different durations of exposure on the four species is 
given below in tabular form. The numbers for the oospores indicate 
the number of bundles ejected from 200 conceptacles. The numbers 
for the bundles of sperms indicate the mean numbers found in one 
drop, i.e., y^th *h e number ejected from 200 conceptacles, or 
approximately the number from one conceptacle. The values under 
the headings “O” were obtained by leaving the seaweeds in water 
for ten hours, then transferring them to fresh sea-water and leaving 
them twelve hours, and then counting the number of bundles ejected. 
I.— Fuchs serratus $ . 
Hours Dry 
4 
3 
2 
1 
i 
0 
78 
21 
118 
45 
29 
43 
27 
54 
13 
14 
8 
12 
- 
21 
23 
7 
_ 
12 
77 
Experiments 
24 
23 
10 
22 
— 
— 
— 
— 
56 
— ... 
Means 
37 
33 
38 
29 
28 
38 
Fuchs serratus 5 
Hours Dry 
9 
3 
2 
1 
187 
67 
64 
28 
Experiments 
151 
140 
72 
52 
171 
240 
— 
18 
Means 
169 
145 
68 
33 
