360 



THE CULTIVATIOX OF DIATOMS 



Montsouris Observatory for the year 1892 — 93 (page 544, etc.), 

 that I need not describe it further here. 



Culture Cells.— For the culture of Diatoms I make use of two 

 kinds of cells. 



The first kind consists of an object-glass, on which is cemented 

 a ring of glass, ground on both its faces, of 5 mm. in height and 

 24 mm, of exterior diameter (Fig. i). This ring is pierced at its 

 upper part with an opening, permitting the introduction of liquids 

 and sowing them. On the upper face of the ring is cemented a 

 thin cover-glass of over two-tenths of a centimetre thick. You 

 thus have a little vessel of two centimetres capacity, where the 

 cultures can be carried on as well as in those of many times its 

 volume. The situation of the aperture on the top of the ring 

 does not allow this litde aquarium to be kept in any but* an 

 upright position. Thus, for the culture of certain Diatoms, espe- 

 cially those that seek the light, you expose the cell with the cover- 

 glass towards the light. At the end of a certain time, varying 

 from weeks to months, the interior of the glass is covered with a 

 light yellow film of living frustules. With the Nitzschia longtssima, 

 for example, which the microscope reveals, the result is truly 

 enchanting. 



. 



Fig. 81. — Microscope Aquarium, half the real size. 

 L Z, Glass Slip, 3x1; O, Aperture in ring ; E E, Culture. 



L„c 



D 



WaE e r.-'i T 



m C m 



Fig. 82.—^, Cell as seen on the microscope, half size. L Z, Glass Slip ; 



E, E, Cell. 

 B, Cell, transverse, half size. Z Z, Glass Slip ; D, Opening of 2 mm. ; 

 c c, Ring ; ni in. Cover-glass ; Z", Culture. 

 C, Cell, longitudinal, half size. Z Z,Xlass Slip ; 0, Aperture ; in in, Cover- 

 glass ; E E, Interior of Cell. 



