NO. 6 KFFECTS OF LKiHT ON ALGAE MKIFR 5 



Meier (1929), while working in Professor Chodat's lal)oratory, 

 conducted a preliminary light experiment in conjunction with an ex- 

 periment relating to the formation of carotin in green algae. Three 

 series of cultures of Chlorclla nibcscciis planted on solid media, 

 Detmer -^ plus glucose 2 percent with agar 1.5 percent, were placed 

 at a north window ; one in the modified diffused light, the second in 

 violet light in a Senehier jar containing copper sulphate, and the third 

 in yellow-orange light, in a Senehier jar containing potassium di- 

 chromate. Chlorophyll production followed l)y formation of carotin, 

 and growth of the cells progressed most rapidly in natural light and 

 least rapidly in the violet light. These results agree with those re- 

 ported hy Sachs on higher plants. 



Arthur (1930) ohserved that plants grown under a red glass filter 

 transmitting no hlue light resembled those grown in a dark basement 

 except that chlorophyll developed. The plants under a blue glass 

 filter transmitting no red were dwarfed but otherwise normal. 



I. EFFECTS OF DIFFERENT INTENSITIES 

 DESCRIPTION OF APPARATUS 



To determine simultaneously the effect of different light intensities 

 on algae under exactly similar conditions of medium and temperature, 

 a large metal table similar to the one pictured in plate i, figure i, 

 was constructed with four glass-bottomed water baths, each holding 

 eighteen 300-cc Erlenmeyer flasks. The four water baths are con- 

 nected to a centrally located thermostated mixing chamber which 

 kept the temperature for these experiments at 21° C. In order to 

 insure uniform dispersion of the algae, a common driving mechanism 

 continuously agitates the Erlenmeyer flasks. The cultures are il- 

 luminated from below by artificial light from Mazda daylight lamps. 



PRELIMINARY EXPERIMENT 



A preliminary experiment was conducted to determine the best 

 growing conditions and the nutrient solution best suited to the algae 

 in this apparatus. The following solutions were prepared : 



I. Detmer (Modified Koch Solution) 



Calcium nitrate i. gram 



Potassium chloride 0.25 " 



Magnesium sulphate 0.25 



Potassium acid phosphate 0.25 



Iron 0.002 



Distilled water i liter 



This solution made up in the above proportions was diluted to one-third. 



