A GLASS CELL. 45 



u little water is taken up in the (lipping-tu])e, and 



r^-C 



\\ 



li 



i--^^ 



r^^C,- '"I 



llyib-(i viridis Avith developed young one, and bud beginning to spruut. 



the cell filled until the fluid stands in a convex 

 heap above its brim. We then select a round glass 



