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THE AMERICAN NATURALIST [Vol. LIV 



the shape and size of the cover glass, with a small cir- 

 cular opening cut in its center, is soaked in hot parafin, 

 drained, and placed upon a glass slide. After the parafin 

 has cooled a drop of water containing the organisms 

 is placed in the center of the circular opening, and the 

 cover glass applied. The drop should flatten out just 

 sufficiently to fill completely the space between the cover 

 glass and the slide inside the circular opening. The 

 cover glass must now be sealed down about its edge by 

 means of a camel's hair brush dipped in hot paraffine. 

 Such a device the writer has called a micro-aquarium and 

 has found its employment of the utmost use. In it scores 

 of Glaucoma were kept alive for as long as eight hours. 



For quieting the movements of Glaucoma thick gela- 

 tine solution was used, and a drop, mixed with a drop of 

 water containing the organisms, placed on a slide and 

 examined under the 16 mm. objective and allowed to re- 

 main uncovered until evaporation had rendered the mix- 

 ture of such viscosity as to retard the animals suffi- 

 ciently. The cover glass was then applied and sealed 

 down with either hot paraffine or castor oil to prevent 

 further evaporation. 



For killing without staining and without distortion 

 either a one per cent, aqueous solution of copper sulphate, 

 a ten per cent, solution of alcohol, or a fifteen per cent, 

 solution of chloretone was found satisfactory. The best 

 of all killing reagents for Glaucoma, however, was found 

 to be a two per cent, aqueous solution of alum. 



Intra-vitam staining was accomplished with an aqueous 

 solution of Bismarck and methyl green ; while for stain- 

 ing after killing there were utilized : iodine, methyl green, 

 methyl blue, Bismarck brown, and safranin. 



The appendages which make Glaucoma of especial in- 

 terest are the oral membranes. These are present in the 

 form of two hyaline, lip-like structures, lying one on 

 either side of the buccal cvaity (Fig. 1). For conveni- 

 ence these will be referred to as the lips. In form they 

 are roughly rectangular, and approximately twice as 



