4 6 



CULTIVATION OF DIATOMS. 



even then three months after planting, these still unfertilised cultivations 

 need only be exposed to the full light of day to spring into visible 

 activity and to become a flourishing colony. From o (c.) to io (c.) the 

 diatoms show perceptible signs of multiplying; from 5 to io the 

 cultivations proceed slowly ; from io to 20 they become luxuriant ; 

 and then at 45 the diatoms are utterly destroyed. 



" Diatoms can be cultivated in a volume of liquid varying from several 

 litres down to 1 c.c. or 2 c.c. ; I have made use of this property to follow 

 the development of these Algae under the microscope and to witness 

 various phases of their generation and multiplication which I shall 

 describe in a future note." 



Dr. Miquel draws a distinction between Ordinary Cultivations in 

 which one or more species are cultivated together lor the purpose of 

 having them constantly at his disposal for any kind of research and 

 Pure Cultivations where a single species is made to pass through all 

 the phases of its existence in order to follow every modification which 

 it would spontaneously undergo, or which can be artificially produced 

 or again in order to cultivate them in such a manner as to be able to 

 make a number of durable microscopical preparations. 



The cultivations are again divided into Cultivations of Fresh Water 

 Diatoms and Cultivations of Marine Diatoms. 



Formula for Solution A. 



A. Ordinary Cultivations of Fresh Water Diatoms. 



Diatoms are cultivated in water containing saline and organic nutriments. 

 The saline nutriments are prepared in two solutions, A and B. 



Formula for Solution B W 

 Sodium Phosphate ... ... 4 gr. 



Calcium Chloride (dry) ... 4 

 Pure Hydrochloric acid at 



22 (c) ... 2 c.c. 



Hydrous Ferric Chloride at 



45 (c) 2 



Water 80 



Magnesium Sulphate 

 Sodium Chloride ... 

 Sodium Sulphate ... 

 Ammonium Nitrate 

 Potassium Nitrate 

 Sodium Nitrate 

 Potassium Bromide 

 Potassium Iodide ... 

 Water 



10 gr. 

 10 



5 



1 



2 

 2 



0-2 

 o-i 



IOO 



( T ) The preparation of Solution A presents no difficulty; Solution B should be made up 

 as follows : To the sodium phosphate dissolved in 40 c.c. of Water are added first the 

 2 c.c. of hydrochloric acid, then the 2 c.c. of hydrous ferric chloride and then the 4 gr. of 

 calcium chloride dissolved in 40 c.c. 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. 



