. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . so added a small quantity of sterilized organic matter. Good cultures were obtainedin this medium, and cultures of single species of diatoms were obtained byfractional subdivision. Allen & Nelson (00) have also obtained excellent results by thismethod, which they say is certain and gives good cultures. These authorshave also used with great success a modification of Miquels culture was found possible to reduce the first solution to
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . so added a small quantity of sterilized organic matter. Good cultures were obtainedin this medium, and cultures of single species of diatoms were obtained byfractional subdivision. Allen & Nelson (00) have also obtained excellent results by thismethod, which they say is certain and gives good cultures. These authorshave also used with great success a modification of Miquels culture was found possible to reduce the first solution to one of potassium nitratewithout detriment, the two solutions being as follows: Solution A. Potassium nitrate 202 grm., Distilled water 100 B. Sodium phosphate () 4 grm., Calciumchloride () 4 grm., Ferric chloride (melted) 2 cc., Hydrochloricacid (pure, concentrated) 2 cc., Distilled water 80 cc. 2 cc. of solution A and Ice. of solution- B are added to each sea-water, and the whole sterilized by heating to 70° C. When coolthe clear liquid is decanted from the precipitate which forms when solution B. Fig. 83. A cell of Surirellaspiralis Kiitz. with eightthick-walled detailed structure ofthe valve is not Cultures and occurrence in nature 115 is added to the sea-water. This medium was found to give constantly satis-factory results without the addition of any sterilized organic matter. The best method of obtaining a culture was to add one or two drops of plankton to250 cc. of the sterilized medium, which was then poured into Petri dishes. These shouldbe left undisturbed and exposed to moderately bright diffuse light. The temperatureshould be kept as constant as possible and at about 15° C. In a few days colonies ofdifferent species of diatoms will be observed on the bottom of the Petri dishes. Thesecan be removed by means of a fine pipette and transferred to flasks containing freshculture medium
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