CULTIVATION OF DIATOMS. 



49 



an aperture near its margin ; it can be kept in a vertical position for the 

 purposes of observation, and in a horizontal position during cultivation, 



f^~:,..,,:,.. ,'.;:;;;; ; :; , ;:;;; l -: 



{ : - f - * .i , ^--rn.r,,-, , , -^ 



m,, o 





 gag 



2 



__ 



rrra 



n 



n 



Fig. 18. The Miquel Cell. 



i. Tranverse section of the Miquel cell. LL. Glass slip. D. Aperture of 2 mm. 

 cc. Cell. MM. Thin cover-glass. E. Liquid of cultivation. 



2. I.ongtitudinal section. LL. Glass slip. O. Aperture. MM. Thin cover-glass. 

 EE. Interior of cell. 



3. Cell as seen on the stage of the Microscope. LL. Glass slip. EE. Cell. 



in which latter case it is then laid flat on the surface of the thin cover- 

 glass. Thus the deposits, instead of being formed on the bottom of 

 the ring, rest and become incrusted on the thin cover-glass; the diatoms, 

 that are planted in these little cells, grow and multiply on the 

 inner surface of the cover-glass, which enables their evolution 

 to be followed for many months with the most powerful immersion 

 objectives. I have some cultivations of this kind which are eight months 

 old, and which still exhibit healthy and vigorous frustular species. 



" To replace the water which slowly evaporates through the apertures 

 of the cells, the volume of liquid is made up to its original amount 

 every eight days with a delicately-tapered pipette, filled with sterile 

 distilled water. 



" By means of this apparatus various re-agents can also be made 

 to act on the Algae by introducing them through the above-mentioned 

 apertures without in any way deranging the position of the cultivation 

 while under the microscope." 



I have myself experimented with these cell cultivations and can testify 

 to the good results obtainable. I will only add, that if the results 

 obtained by Dr. Miquel's arrangements are excellent, still better ones can be 

 obtained by using Mr. Nachet's large inverted microscope, as I am 

 doing at present. By employing this instrument the cell can be left 

 in position during an entire observation without the diatoms being 



E 



