Chapter X: Isolation of Histological Elements 77 



II. MINUTE DISSECTIONS 



A. Alimentary Canal and Nervous System of Insects. 1. Carefully dissect 

 out the alimentary canal of a cockroach and the central nervous system 

 of a grasshopper with the aid of the dissecting microscope or lens. Wash 

 each by gently flooding it with distilled water from a pipette, and then 

 cover it with Gilson's fluid (reagent 15, Appendix B) or corrosive subli- 

 mate (reagent 13) for 5 minutes. 



2. Wash in several changes of water during the course of half an 

 hour and stain for 20 minutes in borax-carmine. 



3. Wash in 50 per cent, alcohol and decolorize in 70 per cent, acid 

 alcohol until the objects become bright scarlet in color. 



4. Wash in 95 per cent, alcohol for 5 minutes and then transfer to 

 absolute alcohol for 5 minutes, xylol or turpentine 10 minutes and mount 

 in balsam. Apply cover and label. 



B. Gizzard of Cricket or Katydid. Pull off the head of a cricket or 

 katydid. The gizzard usually remains attached to the head part. Cut 

 it open lengthwise, wash out the contents and mount as above; only, 

 omit the staining. The inside should be turned uppermost. 



C. Sting of Wasp or Bee. 1. Place a wasp or bee in water, cover to 

 keep out dust and let it stand for two or three days until the smell be- 

 comes unpleasant. 



2. Wash in clear water and squeeze the abdomen gently until the 

 sting protrudes. With forceps pull it out carefully. The poison gland 

 and duct should come away with it. 



3. Place the parts removed on a slide and under a lens draw the 

 sting out of its sheath by means of a small needle which should be 

 drawn over the outer surface of the sheath from the base to the apex of 

 the sting. 



4. Stain and follow out the same subsequent treatment as for II, A 

 or mount without staining. It is advisable to compress the object be- 

 tween two slides as soon as the acid alcohol is washed out. The slides 

 should be tied together and left in 95 per cent, alcohol several hours. 

 Then proceed in the ordinary way. 



D. Salivary Gland of Cockroach or Cricket. Let the animal soak in 

 water as for preparation of sting. When sufficiently decayed pull off 

 the head carefully with forceps. The esophagus, the salivary glands, 

 and crop usually come along with it. Stain and mount as for sting. 

 For preparation of fresh salivary gland see Appendix C, II, " Salivary 

 gland of Chironomous larva." 



E. Mouth Parts of Insect. 1. Place the head of a bee or cockroach 

 in 95 per cent, alcohol for 2 or 3 hours. Transfer to absolute alcohol 

 for 30 minutes, and then to cedar oil for 30 minutes to an hour. 



