114 THE AMEBIC AN MONTHLY [May, 



to the bottom, and also to rise a perceptible distance above it. 

 What use we can make of this peculiarity will be seen later on. 



Of what benefit are they? will be asked by the practical man. 

 We can truthfully say that they are an ultimate source of food for 

 man ; they are eaten by small animals, and these become 

 the food of fishes. Students will recall numerous instances of 

 desmids seen in the stomachs of infusorians. Some small snails 

 eating large closteriums not only satisfied their appetites, but gave 

 a pleasant half hour to the wn'iter a short time since. Their ac- 

 tions were comparable to those of a small cow with a large ear 

 of corn. 



While desmids mav be found at anv season when we can get 

 at the bottom of shallow ponds, the best will be found when all 

 plant life is in vigorous growth. Sink-holes which have no vis- 

 ible outlet, and from which the water never entirely disappears, 

 are generally excellent gathering places. .Shallow ponds, still, 

 shallow coves of lakes, mill ponds, and quiet pools in streams are 

 promising resorts. They may often be plentifully found clinging 

 to the long water-weeds, from which they may be detached by 

 dipping the weeds into a bucket of water and rinsing them up and 

 down. The size of the pool often bears no relation to its impor- 

 tance. A small cavity in low ground, from which the moisture 

 almost but never quite disappears in times of drouth, and which 

 is scarcely two feet across, has produced two new forms. It was 

 formerly the bed of a small granite boulder, and is lined with a 

 growth of sphagnum moss, from which it seems always possible 

 to squeeze a few drops of water, and when driest yields semi- 

 cells of the plants free from chlorophvll and in best condition for 

 examination of their markings. A small depression in a similar 

 place, apparently made by the pressure of an ox's foot, was a 

 valued treasur\' for several months, though it gave no forms new 

 to science. 



The outfit for gathering samples of water need be neither large 

 nor expensive. A dozen one-ounce wide-mouthed round-shoul- 

 dered prescription vials, costing, with their necessary corks, 

 twenty-five cents, a pond-stick cut from the roadside, a hand mag- 

 nifying glasss, costing another quarter, and a small memorandum 

 book are the only requisites for preliminary search. The pond- 

 stick is usually a grey birch about three-quarters of an inch in 

 diameter at the large end, which is flattened on opposite sides for 

 about six or seven inches, split vertically to the flat sides, and a 

 notch cut from the inside of each jaw forming the sides of the 

 split, so that they may securely grasp the neck of the one-ounce 

 vial. Having secured a sufficient number of samples from local- 

 ities whose names and descriptions are recorded in the book, they 

 are taken home and carefully examined under the microscope. 

 Always enter the names of localities in a permanent record, and 

 label each vial with the name of locality and date of gathering. 

 It will save many regrets. If any region gives sufficient prom- 



