TiENIOID CESTODES OF NORTH AMERICAN BIRDS. 9 



According to the size of the worms, the killing solution is allowed 

 to act from ten to twenty minutes, rarely longer. It is then poured 

 off or removed with a pipette and replaced with 70 per cent alcohol, 

 to which enough of a solution of iodine in alcohol is added to give it 

 a sherry-wine tint. If after a day or two all the color has disap- 

 peared from the alcohol, more iodine solution is added, and this is 

 repeated if necessary. When no further extraction of color is appar- 

 ent, the alcohol is poured off and fresh 70 per cent alcohol added, in 

 which the specimens may remain until required for study. 



"V\^ien conveniences required in the technic described above are 

 lacking, tapeworms may be preserved by simply opening the intestine 

 of the bird, spreading it out on a piece of board or paper, scraping off 

 the parasites with a knife and putting them directly into 70 per cent 

 alcohol or 5 to 10 per cent solution of formalin. Less favorable 

 specimens are, of course, to be expected from this method than from 

 the other. 



The label should show the name of the host (it is important that 

 the species of the bird should be accurately determined, and it is 

 advisable to give the common name as well as the scientific name), 

 the locality, the date, and the collector's name. 



Some specimens afford toto mounts favorable for study; in others, 

 on account of the thickness or the contracted condition of the worm, 

 practically nothing can be made out from toto mounts concerning the 

 internal structure, but by pressing a specimen between two glass 

 slides after it has been softened for twelve to twenty-four hours in 

 water and bringing it into strong alcohol again before the pressure 

 is removed, it can generally be sufficiently flattened so that the in- 

 ternal structure becomes more apparent. Before this flattening is 

 done, however, the specimens should be stained, the most generally 

 useful stain being alcoholic acid carmine. The specimens may be 

 stained overnight in dilute stain and then decolorized by soaking in 

 70 per cent alcohol, to which two or three drops of hydrochloric acid 

 to the 100 c. c. have been added. The stage at which to stop decolor- 

 ization can only be determined by experience. After staining and 

 flattening, the specimens are dehydrated, cleared in xylene or cedar 

 oil, and mounted in balsam. Small worms may be mounted entire, 

 larger ones in pieces. If the head is armed with hooks and their 

 shape and size can not be accurately determined in a toto mount, and 

 if a sufficient number of specimens are available, preparations to 

 show these structures may be made by tearing the heads into small 

 pieces with fine pointed needles and mounting in glycerin, glycerin 

 jelly, or balsam. 



In addition to toto mounts serial sections are indispensable in 

 working out the details of internal structure. These should be made 



