OF THE OSCILLATOR!^. 
77 
essential service to the collector, who is enabled by it to 
secure perfectly pure specimens for preservation. As 
stated above, the members of this family delight to dwell 
on the mud, nor can they be got out without a plentiful 
supply of the latter. But this is of little consequence. 
Mud and plants may be thrown together into a vial, and 
on being brought home may be poured out into a deep dish 
with a sufficient quantity of soft water, and then left 
undisturbed near a window. The active little organisms 
immediately set themselves in motion, and creep out from 
among the earthy particles by which they are encompassed, 
forming by degrees a pure thin layer on the surface of the 
water, whence they may be taken up with a spoon, in 
larger or smaller quantities, at the will of the operator. 
Next, for the best method of preparing them for the 
herbarium. This also is made to depend on the movements 
of these singular plants. First, let a sheet of stout paper — 
drawing paper is the best — be provided, and on it describe, 
with pencil and ruler, about eight squares of equal size. 
Fix the paper firmly on a wooden board with needles or 
artists’ pins, and lay in the centre of each square a small 
quantity of soft water. # Let the water spread over a 
circular space the size of half a crown, and then add a few 
drops carefully so as to raise the centre as high as possible. 
By this means the final evaporation of the water is retarded 
to the utmost. Having thus prepared the paper, the next 
step is to deposit in each square a quantity of the Algas, 
taking care to choose portions least contaminated by mud — 
a piece about the size of a bean is sufficiently large. 
Separate the filaments by a gentle touch of the finger, and 
let the whole be left in a spot well exposed to the light. 
Before very long (the time depends a good deal on the 
season of the year, the freshness of the plants, the amount 
* The use of ‘ soft ’ water is insisted on, because the vitality of the 
Oscillatorige is quickly destroyed in hard spring water, and the success 
of these experiments depends entirely on their vegetative principle 
being strong and active. 
