ON THE ARTIFICIAL CULTURE OF MARINE PLANKTON ORGANISMS. 423 



I. CULTUEE OF PLANKTON DIATOMS. 

 A. Practical Culture Methods. 



1. Miqucl's Method. Attention was first directed to the culture of 

 Plankton diatoms ; and the methods, which had been elaborated by 

 Miquel (11) for fresh-water diatoms and had been found by him to 

 succeed with marine-bottom diatoms, were tried. 



The essential features of Miquel's method, as applied to marine 

 diatoms, are as follows : — 



Two solutions are prepared : — 



Forty drops of Solution A and 10 to 20 drops of Solution B are 

 added to each 1000 cc. of sea-water, and the sea-water is sterilized by 

 keeping it at 70° C. for about 20 minutes. 



According to Miquel it is also necessary to add "organic nutritive 

 material in the form of bran, straw, or filaments of weed such as 

 Zostera. Macerations of these should be made up separately, some 

 time before they are required for use, and should be carefully filtered 

 and sterilized. Organic matter must, however, be used very sparingly, 



* '* The preparation of Solution A presents no difficulty ; Solution B should be made up 

 as follows : To the Sodium phosphate dissolved in 40 cc. of water are added first the 2 cc. 

 of Hydrochloric acid, then the 2 cc. of hydrous Ferric chloride and then the 4 grm. of 

 Calcium chloride dissolved in 40 cc. of water, taking care to shake the mixture, which 

 I call Phospho-ferro-calcic solution. The addition of this last solution to the maceration 

 throws down a slight brownish flocculent precipitate, formed for the most part of Ferric 

 oxide, which should be carefully separated from the liquid used for cultivations." 



t " Acid chlorhydrique pur ^ 22\" Presumably meaning degrees Baume = sp. gr. l'I69. 



:!: •' Perchlorure de fer liquide a 45''." As above = sp. gr. 1'421. 



NEW SEIUE3. — VOL. VIII. NO. 5. MaUCH, 1910. 2 G 



