704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



carmine. Finally 33 per cent, alcohol, and then absolute alcohol, 

 are applied, and the specimens mounted in dammar. 



Mounting Gizzards of Insects* — Dr. T. J. Sturt was formerly- 

 content to pull off the head of a cricket, drag with it the stomach, and 

 attached to it the gizzard or organ containing the pyloric teeth, skin 

 off the muscular coat with the thumbnail, cut off any portion of 

 intestine, and then mount. 



This plan, however, missed many interesting points in the stomach 

 and gullet, and he now prefers to kill with a drop of benzine, cut off 

 the extreme tail, pull off the head, cut off the whole intestine, and put 

 it in a 1 oz. phial with 5 or 10 drops of liquid potash. After it has 

 stood about half-an-hour, partly fill with water and shake it well to 

 detach the muscular coat and tracheas ; then slit it up, wash and 

 adjust on a slide. Drain away any moisture, apply a drop of carbolic 

 acid, and place on the thin glass. After a few minutes this will 

 absorb all moisture, and render it quite transparent. If it does not, 

 put a drop of acid at the edge and tilt the slide to drive off the first 

 acid ; then put a little balsam on the edge, tilt the slide, warming it 

 to render the balsam more limpid, and it will gradually take the place 

 of the acid, the lines of demarcation between the two being distinctly 

 visible. 



Preparing Tape-worms, t — Dr. G. Eiehm recommends the follow- 

 ing treatment of specimens. 



To prevent contraction at death, he cleans the living cestode with 

 a brush, and holds it in the hand until it has extended itself under 

 the action of the warmth, and then rolls it upon a glass tube and 

 plunges the whole into spirit ; undue adhesion to the glass is 

 remedied by soaking in water. Such specimens are well adapted for 

 mounting under pressure ; they may be stained with alum-carmine or 

 with heematoxylin ; if with the latter, the specimen should be treated 

 with acetic acid for a minute after staining and then washed in 

 ammonia to remove excess of colour. 



For minute investigation, sections made parallel to the flat surfaces 

 are preferable. To prevent the last sections breaking out of the 

 imbedding mass, this should be made of equal parts of paraffin and 

 white wax with the addition of one or two drops of Canada balsam 

 dissolved in turpentine for each gramme of the mixture. The razor 

 should be wetted with benzine, care being taken not to moisten the 

 object itself too much with the benzine. To secure having the sections 

 cut in the right place, the specimen is soaked in turpentine, placed 

 in a watch-glass of imbedding mass kept liquid by heat, and left there 

 until seen by its transparency to be thoroughly penetrated ; some 

 of the mass is then removed with a hot instrument and placed on a 

 slide and pressed out, the specimen is placed on the stage of the 

 microtome and the slide with its paraffin is placed on it ; when cool 

 the slide may be removed, leaving the specimen imbedded in a 

 strictly horizontal position. The excretory vessels are injected with 



* Engl. Mech., xxxv. (1882) p. 282. 



t Zeitschr. Ges. Naturwiss., vi. (1881) pp. 547-51. 



