210 Modern Microscopy 



breath, and apply a few drops of balsam. Pour off the 

 turpentine from the foraminifera, take up some of the forms 

 on the point of a penknife, and put them into the balsam 

 ■on the cover ; stir up with a needle until spread evenly, 

 -then put away for twelve hours. Bake gently for ten 

 minutes on a hot plate, cool, apply a drop of fluid balsam, 

 -warm a slide over a spirit-lamp, take the cover up in a pair 

 of forceps, and bring the drop of fluid balsam in contact 

 with the centre of the slide, ease down carefully, and press 

 on the upper surface of the cover with a needle-point until 

 it lies quite flat ; or if the forms are very delicate, warm 

 the slide again gently until the cover settles down by 

 its own weight. Allow the slide to cool, then clean away 

 «xuded balsam with methylated spirit, and apply a coat of 

 cement. 



Foraminifera — Opaque Mounts. — Proceed in exactly 

 the same way as directed for mounting dry opaque poly- 

 ■cystina ; but if the specimens are unselected, gum the 

 hottom of the cell, dry the forms on a slide, and spread a 

 quantity of them all over the surface of the cell. Let the 

 gum dry, then shake out all that have not adhered, apply a 

 coat of cement to the upper side of the cell, and when this 

 has nearly dried, apply a cover-glass. 



Spicules of Gorgonia or Sea-fan. — Boil in liq. potassse 

 until all the material has broken up, then wash away the 

 potash with repeated changes of water, allowing the spicules 

 to settle to the bottom of the tube between each washing. 

 "When cleaned, preserve in a bottle of dilute spirit. Pro- 

 ceed with the mounting in exactly the same way as directed 

 ior transparent unselected polycystina. 



Spicules of Alcionium. — Proceed as above. 



Sponges. 



1. To show Cell Structure, Flagellated Cells, etc. — 



Fresh specimens of the calcareous forms — Sycon, for 

 example — should be fixed with osmic acid 1 per cent. 



