So Eee en es ee ee een le a, ee se ee _—" ™ FPR eee ae ee ee Py ee eae 
174 MISSOURI BOTANICAL GARDEN, 
of CO2 would be an important factor in the plant economy. 
Dr. A. Disato (’08), after an investigation along the 
shore of the Mediterranean during the summer of 1907, 
says: “It is significant that the COz content of the air 
over the sea and that over the land are the same (3 parts 
in 10,000), although the conditions are so different. Fur- 
ther, the CO2 content of the sea air in the same region 
remains constant for a number of years by day as well 
as by night. He accepts the theory of Schloessing to 
account for the phenomenon. According to this, the CO 
of the air and the carbonates and bicarbonates of the sea 
remain in equilibrium. The sea serves as a regulator of 
the COz content of the air. By lessening the COz pres- 
sure of the air, new carbonic acid comes from bicarbonates 
of the sea. On the other hand, by increased pressure, COz 
is absorbed and more carbonates and bicarbonates are 
formed in the water. The constancy is further effected 
through transportation by the wind. 
Dr. Disato made further investigations as to the oxygen 
content of shore waters. He found that the amount of 
oxygen dissolved in sea water at Concarneau fluctuated 
between 16 and 20 mg. or parts per million, or about 11 
to 14 ce. per liter. This large amount is explained by the 
shallowness of the water along the coast and by the carpet- 
like colonies of alge which cover the ground to a great 
extent in the shallow waters, and in sunlight are able to 
produce an abundance of oxygen. The best proof of this 
hypothesis is the fact that the amount of oxygen is greatest 
during long continued sunshine. 
The extensive investigations of Whipple and Parker (’02) 
on ponds and reservoirs under their care, point to a very 
close relationship existing between the gas content of the 
water and the periodic growth of the phytoplankton in 
these waters. This is especially noted in the spring and 
autumn maxima of diatoms. The fluctuations in gas con- 
tent are very much influenced by the movements of the 
water on a large scale, known as “overturning,” at these 
times. 
