6b OF THE STIPITATE DIATOMACE.E. 



If the contents of the slide are not likely to be disturbed, 

 after having been once deposited, or if the valves will not 

 readily attach themselves to the slide, it is better to cover 

 them at once and permanently with thin glass, drawing a 

 ring of Brunswick Black round the edge of the latter, to 

 exclude the air. 



