ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 511 



1. Pour xylol on warmed slip to dissolve the wax. 



2. Pour absolute alcohol from corner of slip downwards, so that it 

 drives off all xylol. 



3. Place in dish of water for three minutes. For acid haematoxylin 

 this must be distilled water. 



4. For iron alum staining, remove the slides and place on each 

 several drops of iron alum solution, and allow to stand for ten minutes. 



5. Pour off iron solution and place in dish of clean water. Use 

 plenty of clean water for each operation, 



6. Remove slips and pour on drops of aqueous solution of hema- 

 toxylin. Stain for ten minutes. 



7. Place slips again in clean water. 



8. Now take each slip in turn, and with a glass rod apply drops of 

 alcohol and HCl. The stain of specimens then turns red ; the amount 

 of de-staining required can only be learnt by experience, otherwise all 

 the stain may be washed out. The slips are then again placed in a 

 dish of clean water, when the stain again turns blue or black by the 

 action of the tap-water. 



9. Remove slips and pour on erythrosin (alcoholic) or any alcoholic 

 counter-stain. 



10. Wash off excess of stain with absolute alcohol. 



11. Place in clearing-bottle of xylol. Old metal shaving-soap boxes 

 make excellent clearing-tubes, as they are lined with paper, and do not 

 corrode with action of xylol. 



12. The slips may be removed after eight or ten hours, and finally 

 mounted in xylol and balsam and dried in the usual manner. 



For staining with acid hsBmatoxylin, after the distilled water place 

 some acid hematoxylin on each slip, and allow to stain for ten minutes ; 

 then wash off excess of stain in distilled water and transfer to dish of 

 tap-water, where red stain turns blue. When this has occurred, remove 

 slips, and counter-stain. Dehydrate, clear, and mount in balsam. In 

 this method the stain attacks the film of albumin in the slip. To rid 

 the slide of this, place in weak acid alcohol, and then finally wash with 

 tap-water till the colour reappears. 



Another method of fixing the ribbons to the sUp may be of use. 

 First place 1 p.c. solution of gum arable on the slide ; place the ribbon 

 in and flatten. Drain off excess. Now irrigate from corner of ribbon 

 with weak solution of bichromate of potash, expose to light for an hour, 

 and finally dry off in an oven. For botanical specimens of a woody 

 nature, it is said that this is a never-failing fixative. 



With regard to mounting insect subjects, the author has made some 

 attempts to mount specimens of the proboscis of the blowfly. This is 

 done by first putting the fly under ether ; then take the head and gently 

 press it, when the proboscis will shoot out. Press a cover-glass over 

 this on to a slip, and cut off at the base of the trunk. Irrigate with 

 alcohol, which fixes the tissues ; then clear in potash, wash out alkali, 

 arrange parts, and place in alcohol again. Then transfer to turpentine 

 to clear. Finally, mount in balsam. 



With most insect parts the author used varying strengths of potash, 

 according to subject in hand. Heat appHed to the slide is often useful 

 in this branch of work for removing air bubbles. 



