ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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production in these genera. The germinating zoospores produce two 
hinds of gametophytes, multicellular germlings, one kind large-celled, 
the other of much smaller cells. The sexual generation was first noticed 
by Sauvageau in Sacchoriza. Lloyd Williams is now in a position to de- 
scribe the discharge of the antherozoids and the process of fertilization, 
and also the process of dehiscence of the oogonium and the libera- 
tion of the eggs, for Laminaria and Chorda respectively. A. G. 
Variation in the Number of Ribs in Costaria costata. — 
Catharine W. Smith {PuM. Puget Sound Biol. Station , 1919, 2, 
307-12, 1 pi.). An account of the variations found in the ribs of a 
large number of fronds of this species gathered in Puget Sound. The 
frond is usually stated to have 3-5 ribs ; but in the series examined the 
number of ribs in mature fronds ranged from 4 to 9. In 4-ribbed 
fronds the typical midrib is absent. The midrib may disappear in part 
of a frond and reappear again below (the growing region is at the base 
of the frond). The side ribs may split into two or more, forming 
groups. No explanation of the variation is attempted. A. G. 
Age of Pterygophora californica.— T. C. Frye (PuM. Puget 
Sound Biol. Station , 1918, 2, 65-70, 1 pi.)* A consideration of the 
evidence afforded by the rings of growth in the stalk of Pterygophora 
as to the age of the plant. Examination shows that there is a relation 
between the rings and the annual production of fronds. The rings 
appear to be annual growth rings, and the greatest number observed in 
any specimen was 21. Some other kelps show rings. A. G. 
Relation between the Osmotic Pressure of Nereocystis and the 
Salinity of the Water. — Annie May Hurd (PuM. Puget Sound 
Biol. Station , 1919, 2, 183-93). The osmotic pressure of this alga is 
intimately related to the concentration of the sea water, and decreases 
ns the water becomes less saline. It will not tolerate a sudden change 
to fresh water, but can be gradually acclimatized to fresh water if the 
cell sap is allowed time to become adjusted to the outside concentration. 
The osmotic pressure of the plant in normal sea water as determined by 
the freezing-point method is 22*72 atmospheres. The osmotic pressure 
of Puget Sound water averaged 19 2 atmospheres. Throughout the 
adaptation of the cells of the plant to fresh water they maintain an 
average osmotic surplus of 3*62 atmospheres. The lowering of the 
osmotic pressure as the plant adapts itself to increasing dilutions of sea 
water is brought about (1) by the outward diffusion of salts, and 
(2) by the increased intake of water. A. G. 
Extraction and Separation of the Pigments of Nereocystis 
Luetkeana. — Grace E. Howard (PuM. Puget Sound Biol. Station , 
1921, 3, 79-91). The object of the research was to find out what 
pigments could be extracted from Nereocystis , and at the same time to 
test Willstatter’s statement that the lower plants contain the same four 
pigments as the higher plants. Willstatter’s methods were used. The 
results are as follows : — 1. Pigments which can easily be extracted from 
kelp are chlorophyll A, chlorophyll B, carotin, xanthophyll and fuco- 
xanthin. The first four are found in the higher plants. 2. Magnesium 
