64 Sarah M. Baker. 
sufficient to remove some of the delicate hairs. The block of ice 
was broken off the one receptacle, and then both were exposed 
for a definite time, put into seawater, and the number of bundles 
of gametes expelled from each counted. The results of a series of 
ten experiments with Fucus spiralis are shown in the Table on p. 63. 
The mean values are :— 
$ Iced 7 bundles expelled. Check = 12 bundles expelled. 
? Iced = 60 „ „ Check = 100 „ „ 
The values in italics are the only cases in which the iced 
receptacle does not show less dehiscence than the check. The 
mean values do not exhibit so large a difference as that given 
by the waxing method, though this may be partly due to the fact 
that they were made with material from a different locality, and 
at a different time of year. It appears, therefore, that the para- 
physes play an important part in the extrusion of the gametes; the 
removal of some of them, and the consequent disarrangement, 
being sufficient to affect the mechanism considerably. 
Another series of experiments was made at White Cliff Bay 
in which the receptacles, dried in the usual way, were allowed to 
extrude their reproductive bodies into fresh water instead of sea¬ 
water. If the swelling of the paraphyses plays a part in the 
mechanism, the smaller osmotic pressure of the fresh water should 
cause them to swell up more and hence to expel more gametes. 
No. 
MALE. 
FEMALE. 
No. 
MALE. 
FEMALE. 
F.W. 
S.W. 
F.W. 
S.W. 
F.W. 
S.W. 
F.W. 
S.W. 
1 . 
7 
1 
91 
35 
VII. 
16 
4 
48 
29 
II. 
8 
3 
171 
92 
VIII. 
13 
7 
86 
62 
III. 
13 
6 
109 
73 
IX. 
3 
3 
78 
80 
IV. 
15 
6 
137 
99 
X. 
4 
4 
96 
64 
V. 
1 G 
9 
138 
61 
XI. 
3 
2 
66 
74 
VI. 
19 
3 
92 
67 
XII. 
2 
1 
54 
33 
As it must often rain when the plants are exposed by the tides, 
they must be accustomed to the action of fresh water. The values 
found using Fucus spiralis are shown in the Table. The check 
values with seawater were done with the twin receptacle to that 
used for the fresh water, as in the former experiments, 
