422 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
is present in chlorophyll. 3. There is good evidence that chlorophyllase 
is present. 4. Kelp chlorophyll can be put into a colloidal state. 
5. This colloidal chlorophyll carries a negative charge. 6. These 
pigments cannot be extracted by pure solvents. A. G-. 
Experiments with Fucus to Determine the Factors Controlling 
its Vertical Distribution. — Floyd W. Gail {Publ. Puget Sound Biol. 
Station, 1918, 2, 139-51, 1 pi.). An account of experiments made on 
Fucus evanescens, the results of which are as follows : — 1. Mature 
plants are more resistant to lower light intensities than are sporelings. 
2. Desiccation of young plants is believed to prevent the growth of 
Fucus on gravel. 3. Reduced light intensities cause the death of well- 
grown plants 1 metre below the surface of the water. 4. Well-grown 
plants receiving less than quarter total light become darker in colour, 
and decomposition takes place. 5. Reduced light causes the death of 
oospores and sporelings when planted more than 3 decim. below the 
surface of the water. 6. Light is a controlling factor in determining 
the lower limit of Fucus . A. G. 
Hydrogen Ion Concentration and other Factors affecting the 
Distribution of Fucus. — Floyd W. Gail {Pull. Puget Sound Biol. 
Station, 1919, 2, 287-306, 2 pis.). Experiments showed that the 
growth of sporelings and mature plants of Fucus is almost completely 
inhibited in sea water having a higher pH value than 8 ’6, and is much 
inhibited at 8 • 4 ; also at 8 * 6 and at a temperature above 24° C. these 
plants cannot live. Also when the pH value falls below 7*2 their 
growth is inhibited ; and they are killed when the pH value falls to 
7 * 0 and the temperature exceeds 24° C. Fucus does not grow on 
beaches where there is much Ulva, since the latter caused the sea water 
to have too high a pH value. The plasma membrane of oospores is 
sufficiently permeable to OH and H ions in sea water having pH values 
above 8 * 4 and below 6 * 8 to reduce the percentage of germination, and 
to inhibit the growth of sporelings. Fucus is not found on smooth 
gravel beaches (even where Ulva is not present) since the high tem- 
peratures and extreme desiccation decrease the germination and prevent 
the growth of sporelings. The oospores do not germinate in water of 
pH value 7'0, if the temperature is as high as 30° C. for 3 hours or 
more, and they are retarded at lower temperatures with pH values 
below 7 * 2. Fucus is absent from tide pools because the temperature is 
too high, and the extremes of the pH values are too far apart. Re- 
duced light is a controlling factor in determining the lower limit of 
Fucus. The probable low pH value and low oxygen content of the 
sea water at any considerable depth may also be important factors. 
A. G. 
Taxonomy and Morphology of the Ligulate Species of the Genus 
Desmarestia. — Vinnie A. Pease {Pull. Puget Sound Biol. Station, 
1 920, 2, 313-67, 10 pis.). The ligulate species of Desmarestia are here 
discussed — namely, D. ligulata Lamour.,Z). lierlacea Lamour.,Z). latissima 
Setch. & Gardn., and D. foliacea Pease, the latter two being described 
t nd figured for the first time. A key to these species and D. yinna- 
tinervia Mont, and D. talacoides Okam. is provided. The rest of the 
