and Laboratory Methods. 2553 



At the formal opening of the laboratory addresses were made by Prof. J. W. 

 Denny, Dean of the College of Arts, Philosophy and Science, O. S. U.; Capt. 

 Alexis Cope, Secretary of the Board of Trustees ; John T. Mack, resident trus- 

 tee ; Prof. Herbert Osborn, the director; and Prof. C. J. Herrick, of Denison 

 University, President of the Ohio Academy of Science. Mel T. Coor. 



DePauw University, Greencastle, Ind. 



The Technique of Biological Projection and Anesthesia of 



Animals. 



Copyrighted. 



XVIII. DIRECTIONS FOR MOUNTING LIVE ORGANISMS IN GLASS 



CELLS—Continued. 



Mounting plant specimens for demonstrating the circulation of protoplasm in 

 their cells. 



For this interesting, but somewhat difficult experiment, any one of a number 

 of different species of plants, including chara, nitella, tradescantia, may be used. 

 If chara or nitella are to be used, select rather young, vigorous leaves from 

 whorls near the apex of the stem and study their terminal cells. Different 

 species of purple tradescantia, or spiderwort, have numerous fine hairs attached 

 to each stamen. The cells composing these hairs have transparent walls and 

 the cell contents show a natural differential staining. The streams of finely 

 granular, transparent, or silvery, protoplasm circulate through a purple 

 colored sap. 



In mounting specimens for this experiment, great care must be taken that the 

 cells are not killed by rough handling, drying, or pressure of the cover-glass. As 

 soon as it is mounted, examine the specimen under an ordinary compound 

 microscope and note the location of the cells which show the circulation best, 

 and transfer the slide to the projection microscope, which should have the light 

 and approximate focus already adjusted for the work. This use of an ordinary 

 compound microscope with very difficult or delicate objects for locating the parts 

 having special interest saves time and specimens, and enables the operator to 

 know how much is to be expected from an object. 



B. Directions for mounting various organisms, e. g., hydra, gammarus, 

 daphnia, cydops, planarian worms, leeches, larvae of insects, small snails and 

 crayfish, and plant specimens, in hollow-ground cells and ring cells. 



In this class of work two difficulties frequently arise at the same instant ; a 

 lively animal attempts to escape from the cell and air bubbles enter the cell 

 while the cover-glass is being placed in position ; but success is easily attained 

 by the method here given. 



Having selected and thoroughly cleaned a cell deep enough to hold the 

 organism (Fig. 9, either No. 2, 3, 5-9, 11-13, 21, or 22), and a cover-glass free 

 from flaws and large enough to considerably more than cover the hollow, 

 partially fill the hollow with water and place the organism in it. Lay the cover- 



