2126 



Journal of Applied Microscopy 



elementary and higher courses in zoology, as they exhibit in a remarkably clear 

 manner, when under chloretone, most interesting and important details of struc- 

 ture and functional activities, and a wide variety of tissues. They are readily 

 kept alive in the laboratory throughout the entire year and their manipulation is 

 very easy. Under the influence of the hypnotic, they are perfectly passive in a 

 compressor, and every point in their anatomy may be seen with the compound 

 microscope while studying the functional activity of the circulatory and digestive 

 systems. 



For these fascinating studies, the smallest and most transparent worms are 

 to be chosen. Specimens not over two inches long and having a pink tint are 

 best. Wash the worms thoroughly in two or more changes of water, and, if time 

 permits, clear the alimentary canal of most of its dark colored contents by plac- 

 ing the worms, for a day or two, in a deep covered jar with a quantity of wet, 

 clean, white filter paper torn into bits. Lift the animals with a bent needle and 

 place them in a tray with a measured quantity of water sufficient to cover them. 

 Add one-fifth as much one per cent, chloretone solution as there is water. The 

 worms squirm actively for a minute or two, but in three minutes are ready for 

 study with hand lens or compound microscope. The best results are obtained 

 by slightly flattening the worms in a compressor. A simple and very satisfac- 

 tory method of mounting them is 

 shown in the accompanying illustra- 

 tion. This gravity-compressor con- 

 sists of a base plate of ordinary win 

 dow glass about four by one and a 

 half inches. On this place an ordinary 

 three by one inch slide. On the slide 

 place a few drops of chloretone and 

 water from the tray along with an 

 earthworm. Arrange the worm with 

 dorsal, ventral, or lateral side up, as 

 desired. Across the ends of the slide, 

 place strips of filter paper one fourth 

 inch in width and of enough thick- 

 nesses to equal half the thickness of 

 the worm. Moisten the filter paper 

 with the same strength of chloretone 

 solution as used on the worm and 

 drop a little more on the worm, if it 

 is not well surrounded by the liquid. 

 Place another slide over the worm, 

 letting its ends rest upon the strips 

 of filter paper. The weight of the 

 upper slide flattens the worm so that 

 its anatomy is readily seen with any objective having a working distance not less 

 than the combined thickness of the upper slide and the compressed worm. In 

 the illustration a three-fourths inch objective is shown focussed on the " hearts," 



Fig. o. — Live Earthworm in Gravity-compressor. 



