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iSit tbe Cultivation of 2)iatoin0 b^ artificial 



fIDeans. 



By Dr. Miguel. 



Translated from Le Diatoiniste. 



Plate VIII. 

 Part 11. — On the Artificial Growth of Marine Diatoms. 



IF the experimenter is near the sea^ he will use natural sea- 

 water for the growth of Marine Diatoms ; but if he has at 

 hand only soft, or river water, he must add the undermen- 

 tioned salts in the following proportions : — 



Soft Water (rain or distilled) ... looo c. 



Common Salt (Na. CI.) ... ... 25 grms. 



Sulphate Magnesia ... ... 2 grms. 



Chloride Magnesium ... ... 4 grms. 



This artificial sea-water, which, like the natural water of the 

 sea, may perhaps be somewhat modified as to its composition, 

 readily lends itself to the growth of Diatoms. In my comparative 

 experiments this compound has often given finer growths than 

 the natural sea-water, and sometimes the reverse has been the 

 case. But whether it be natural or artificial sea-water, there is in 

 them little of nutriment for the Diatoms, whose behaviour in this 

 respect is similar to that of Fresh-water Diatoms. It is, therefore, 

 necessary to add to them the solutions described as A and B^^ 

 and also organic substances in suitable quantities, as bran, straw, 

 or some ribands of the yastera, commonly called " vraick." 



In some cases, in order to obtain precise comparative results, 

 you should make, two or three weeks in advance, a nutritive 

 maceration, filtered ; and also a fluid sufficiently charged with 

 nitrogenous substances. In all cases sterilisation must be effected 

 at yo^C. But you must be very careful how you add to the sea- 

 water gelatinous lichen or other marine plants (either fresh or 

 dried) from muddy localities. In a word, if you wish to imitate 

 what takes place in Nature, and you yield to this desire, you will 

 obtain such a putrescent medium, that in twenty-four hours the 

 Diatoms that you have sown will be irremediably destroyed. In 



* See page 37. 



