118 STUDIES OF PHOTO-SYNTHESIS IN MARINE 



and even by any delicate marine animal organism, such as a de- 

 veloping embryo plaice or a fertilised echinus egg. 



The increase of hydroxyl-ion concentration and corresponding 

 decrease in hydrogen- ion concentration are such that the water 

 shows a full pink with phenolphthalem, and is more alkaline than 

 the full strength of the decinormal " alkaline phosphate " (Na 2 HP0 4 ) 

 in the Sorensen phosphatic mixtures for determination of hydrogen- 

 ion concentration. This means, expressed in the usual logarithmic 

 notation, a concentration of less than P H , 10~ 9>1 . 



This increase of alkalinity is about equal to that shown in 1905 

 by Moore, Roaf, and Whitley, 1 to promote disordered cell division, 

 and, later, death in the dividing cells of fertilised echinus eggs. 

 Now, when the sunshine is strong in spring and summer, in every 

 pool upon the seashore above half-tide level, when isolated from the 

 sea, such active photo-synthesis must proceed with development 

 of alkalinity, and such changes must have a marked effect upon any 

 animal forms of life in the pool. Such environmental changes, with 

 their stimulating action upon cell division, may play a part in 

 originating deviations and producing variations. In winter such 

 influences would be slight, but as the spring days lengthen and the 

 altitude of the sun increases their power augments and reaches a 

 maximum just as reproductive processes and rapid cell division are 

 at their height. In the experiments recorded below, in order to 

 prevent death from alkalinity, a supply of carbon dioxide was given 

 by blowing air from the lungs through the sea water in which those 

 algae were immersed which were exposed to full day or sunlight, 

 whenever the titrations showed an approach to the lethal limit. 



The main series of experiments was carried out during the period 

 of March 28 till April 5, 1919, in two sets of twelve each of the 

 Kilner fruit-preserving jars, each of about 800 c.c. capacity and 

 provided with airtight, screw-down lids, as described in a previous 

 chapter. Afterwards, for purposes of analysis, the two sets at the 

 end were combined and preserved together. As there were two 

 similarly treated jars in each set, the Kjeldahl determinations for 

 nitrogen came to be made upon the contents of four jars; thus a 

 good average was obtained. 



The green seaweed utilised was Enteromorpha compressus, which 

 grows abundantly in the open wooden runnels supplying the freshly 

 pumped-up sea water to the ponds of the Fish Hatchery at the 



1 Moore, Roaf, and Whitley, Roy. Soc. Proc., B, vol. Ixxvii., p. 102 (1905). 



