Fritsch.- — The Moisture Relations of Terrestrial Algae . 1 . 3 
B. The Loss of Moisture by Wet Material. 
If wet material of any of the algae employed is allowed gradually to 
dry exposed to the air, but screened from sunshine and atmospheric 
precipitations, it loses moisture, rapidly at first and then more and more 
slowly, until a weight is reached which varies only about a constant value 
in relation to the moisture-content of the air. At this stage the algal 
material presents a perfectly dry appearance like that assumed in nature 
during periods of drought ; the dark green colour of the wet alga is 
replaced by a dull green. In summer this dry state is reached in the 
space of two or three days, in winter the time interval may be considerably 
longer. It will be evident, therefore, that during the summer months the 
beneficial effects of direct wetting by rain are of but short duration. 
Drying does not, however, take place at the same rate in the different 
algae under consideration, a fact shown by the data given in Table I. In 
this experiment the different materials used were first thoroughly soaked 
in water and then placed in funnels for some hours until the excess moisture 
had drained off. They were then exposed to the air in evaporating dishes in 
the laboratory (av. temp. 13 0 C.) and weighed at frequent intervals. 
Table I. 
Results of successive weighings (between 10 a.m. and midday on each day) 
of soaked masses of various algae, &c. The weights are given in 
grammes. Attainment of air-dry weight indicated by heavy type. 
Zygnema 
Honnid. 
H or mid. 
Pleuro- 
Pleitro- 
ericet . 
stage. 
stage. 
coccus. 
coccus. 
1 1 *973 
25.592 
— 
9.904 
— 
10-788 
24.164 
19-626 
8.631 
11-411 
9.560 
22.766 
18. 180 
7.526 
9.989 
7.828 
20.558 
16*509 
6-691 
8.819 
5.962 
18.483 
I 4-736 
6.247 
7.892 
4 - 33 i 
16-429 
12-901 
6-202 
7-332 
2.83T 
13-974 
10.305 
6-215 
7^98 
2-22 I 
12.054 
8*577 
6151 
7* 1 33 
2-148 
9.470 
6-185 
6*135 
7-106 
2-151 
7.207 
4.076 
6.150 
7 -H 3 
2.146 
4-835 
2.657 
6.134 
7.089 
2.168 
3.230 
2.429 
6-169 
7 -H 7 
2.161 
2*534 
2-416 
6.156 
7.101 
2-141 
2-484 
2-385 
6-130 
7-060 
— 
2.494 
2.396 

— 
2.136 
2.479 
2.387 
6-121 
7-068 
Spiro- 
Clado- 
Cotton- 
Cotton- 
Soil. 
gyra. 
phorad 
wool. 
wool. 
— 
— 
24.369 

— 
13.266 2 
12-622 2 
22.479 
24.193 
33 - 95 2 
12.293 
10-224 
20-683 
21-807 
31.649 
10.677 
7-385 
18-609 
17.607 
29.060 
9.047 
3-555 
16.266 
15-301 
26-603 
7-334 
2-061 
13.604 
10-992 
24.800 
4-933 
0*751 
9.891 
5-795 
24.452 
3-508 
0-620 
7-207 
3-771 
2 4-353 
1.766 
0-616 
3 - 9 L 3 
2*0l6 
24.308 
0-690 
0.616 
2.125 
1 -97 1 
24-310 
0623 
0*613 
2-073 
1.954 
24.283 
0.637 
0.620 
2.094 
1-968 
24.297 
0-629 
0-618 
2-081 
1-955 
24.287 
0-622 
c-6i 1 
2.071 
1.948 
24-262 
0-621 
0-609 
2.065 
1.940 
24.241 
1 A certain amount of a narrow species of Oedogonium also present. 
2 Weighed on this day at 3*45 p.m. 
