OF THE OSCILLATOPJ.E, 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 Algse, 

 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 

 Oscillatorise is quickly destroyed in hard spring water, and the success 

 of these experiments depends entirely on their vegetative principle 

 being strong and active. 



