76 
L. Beesley. 
a. 
Fig. 74 . 
Diagram of Second Form of Apparatus, in median longitudinal section. 
a, lead spiral; b, porcelain trough. 
half filled with Alga-covered sand grains, and the tubing thus covered 
by a layer of about 6 ins. of sand. When a current of water 
was turned on, about twenty small springs were formed, and the 
whole mass of sand grains was kept bathed and in motion by 
fresh supplies of water, thus more nearly imitating the natural 
conditions. Coverslips were placed upright in the sand, on which 
the Alga grew freely. 
For the study of the life-history of the Alga on the coverslips 
the following method was employed :—A culture cell (Fig. 75) with 
rather wide arms was selected and firmly cemented down to a glass 
slide by means of sealing-wax. Through one of the side arms of 
the cell was passed a piece of fine glass tubing, which was turned 
.a. 
Fig. 75 . 
Diagram of culture-cell and method of culture. a. Coverslip with 
Alga growing on the under surface; b, glass slide; c, fine glass tube 
through which water is supplied to a. 
upwards at the end as it entered the cell and ended in a fine hole, 
so that this hole was just on a level with the upper open surface of 
the cell. A rubber joint made connection between the glass tube 
and the arm of the cell. Coverslips with the Alga growing on 
them were placed face downwards on the open mouth of the cell 
so that the turned-up end of the glass tube was just touching the 
coverslip. A current of water, controlled by a screw-clip, was 
passed through the fine glass tube and emerging by the small hole 
