44 CULTIVATION OF DIATOMS. 



Dr. Macchiati published a note ( ' ) on the cultivation of diatoms on 

 the 22nd March, 1892, but this little work only contained theoretical 

 data, and gave no precise directions which couid guide the worker. 



On the other hand, Dr. P. Miquel, whose papers on the repro- 

 duction of the sporangial form have been previously mentioned, has 

 published in Le Diatomiste and in the Amiales de Micrographie, a 

 series of articles in which all the questions relating to the cultivation 

 of diatoms are examined in detail. The manuscript of the former of 

 his articles was sent to Le Dialomiste on the 30th January, 1892. 

 The French observer may therefore just claim priority in producing 

 artificial cultivations of diatoms, which are destined to play so important 

 a part in the iuture study of diatoms. 



Dr. Miquel has laid before the Academy of Paris a paper in which 

 he lays down general directions for cultivating diatoms ( 2 ). We shall 

 now proceed to reproduce this paper, and then make a summary of the 

 various publications by Dr. Miquel, on the subject under consideration : 



"The silicious phaeophyceae of the family of Diatomacese," says 

 Dr. Miquel, "which hitherto have never been artificially cultivated, can 

 nevertheless be cultivated in laboratories just like other microscopical 

 plants. 



"From a careful chemical analysis of the fluid media, in which 

 these algae are usually found growing in nature, I have drawn up a 

 few instructions which have been invaluable in enabling me to ascertain 

 the composition of the nutritive macerations which favour the multi- 

 plication of diatoms. 



" Ordinary water when placed in glass jars, containing pieces of 

 stalks of grass, husks of wheat, barley, oats, &c, and fragments of 

 mosses, is rendered very favourable to the reproduction and multiplication 

 of fresh water diatoms. The excrement of rodents and ruminants may 

 also be used for the same purpose, but the latter are more inclined to 

 favour the development of Chlorophycege than of Phaeophyceae. Fleshy 

 muscle, washed and cooked, may also be used to charge the macera- 

 tions with organic matter, but with much less success. The effect of 

 adding to the cultivating media, soluble hydrates of carbon, albuminoid 

 substances, white of egg, blood serum, gums, gelatines, &c, is either 

 negative or else harmful, since a certain number of fungi are sown 

 with the diatoms. 



( * ) Dr. L. Macchiati : Communicazione preventiva sulla cultura della Diatomee. Extratto 

 dagli atti della Societa dei naturisti di Modena. Ser. III., Vol. XL, 1892. 



( a ) De la culture artificielle des Diatom^es par M. P. Miquel, 28th March, 1892. 



