and Laboratory Methods. 1409 



particular form of net, whether it be one serving for the collecting of insects, 

 .minute or large aquatic animals, and either Birge net, dip-net, sieve or scoop. 



Explanation of Figures. 



Fig. 1. — The upper part of the net with the upper margin of the cloth " leg." 

 Fig. 2. — The ring which clamps it to the handle. 

 Fig. 3. — Method of clamping suggested. 

 • Fig. 4. — The collecting cup at the lower end of the cloth " leg." 



r, Ring of wire for attaciiment of cord if net is to be used in casting. 



rt, Same wire carried down and soldered to the wire ring 



w, whicii forms the rim at the base of the cone of gauze netting, c. 



a, Mass of lead at the tip of the cone to add weight. 



t, Short tin cyHnder soldered to the base of the cone, with a groove at the upper end (g) 



and a flange at the lower (f), over which is fastened the end of the cloth "leg " of 



the net. 

 n, The cloth " leg," which is about eighteen inches long, tapers toward the lower end, and 



is made, as before indicated, of cheese-cloth and China silk, 

 cl. The clamping ring, the end of which (cle) is soldered to a block (b), which in turn is 



capable of being fastened firmly to a base (ba) by a screw (s) fitting into a hole (sh). 



In the writer's nets these parts are all of brass. 

 1, Cup at lower end of the "leg" made of lead pipe flared at the upper rim and grooved 



near this rim for tying of the " leg." 

 st, Screw top such as is used for kerosene cans. The material is accumulated in the cup 



and then by unscrewing of the cap allowed to run into a bottle, can, or vial as may 



be desired. 

 Zoological Laboratory, University of Nebraska. ROBT. H. WOLCOTT. 



A Method of Determining the Comparative Gravity of Alcohol 

 when Dehydrating by Osmosis. 



In dehydrating by osmosis it is not always easy to tell when the two fluids 

 have reached an exact balance. The following simple method is very accurate, 

 and practically no trouble at all. When it is thought that a balance has been 

 reached, take a couple of drops of the dehydrated fluid in a dropping pipette, 

 and carefully drop it into the dehydrating fluid. If there is any difference in the 

 gravity of the two fluids the drops will descend to the bottom with the peculiar 

 oily appearance always seen upon the mixture of two grades of alcohol. If the 

 grades are equal, however, the drops will not be seen after touching the surface. 

 Chicago. R- P- Woodford. 



A simple plan of preparing permanent specimens to demonstrate any desired 

 structures in the earth-worm, is to place the specimen, after careful dissection, 

 into glass .tubes of suitable size, one end of which has been sealed with a flame 

 before the specimen is inserted, the other corked and sealed with sealing wax 

 after the tube containing the specimen has been filled with 3 per cent, formalin. 



