NO. 6 EFFECTS OF LIGHT ON ALGAE— MEIER II 



This table was constructed with four ghiss-hottonied water l^aths 

 each holding six ;^oo-cc Erlenmeyer flasks. Each flask is enclosed in 

 a container with a light filter on the bottom. (See pi. 3, fig. 2.) The 

 holders containing the flasks are maintained in continuous agitation. 

 Each filter is one of a duplicate series of 12 short wave length cut-oft' 

 filters, that is, a set which transmits progressively shorter and shorter 



Taule I. — SJwrt Wave Length Cut-off Filters^ 



Cut-off 

 Name of filter A 



Heat resisting pyrometer red, 62 percent 6000 



Heat resisting red, 130 percent 5900 



Heat resisting red, 245 percent 5800 



Heat resisting lighthouse red, 100 percent 5600 



Heat resisting yellow, red shade 5200 



Heat resisting yellow, medium shade 5000 



Heat resisting yellow, yellow shade 4800 



Heat resisting Noviol 4600 



Noviol " C " 45.00 



Noviol " O " 4000 



Nultra , 3700 



=> These filters are made by the Corning Glass Company. 



wave lengths from one transmitting only deep red to the other ex- 

 treme where the whole region is included, as shown in table i. One 

 special filter is included in each set. Each flask containing its in- 

 oculated culture of Stichococcus hacillaris was placed in the con- 

 tainer, which cut out all light except that entering through the glass 

 filter. For the sake of convenience, one set of cultures is indicated 

 north side (N) and the duplicate set, south side (S). 



EARLY EXPERIMENTS 



Five experiments were conducted in this apparatus. The results of 

 the first two experiments are questionable, since the light intensity 

 measurements taken through the various filters at the close of the 

 experiment were found to vary as much as 50 percent from the 

 original measurements. The experiment was attempted a third time, 

 care being taken to clean the flasks and filters daily and also to observe 

 any change in light intensity with a photoelectric cell and to correct the 

 intensity changes accordingly. After the experiment had run for 10 

 days, the belt of the motor governing the circulation of water broke 

 during the night. By morning, the temperature of the cultures had 

 risen to 120° F. and as the majority of the algal cells were found to be 

 deformed, colorless, or exuding their chlorophyll, the results of this 

 experiment were also discarded. 



