88 
Psyche 
[December 
1. Two days in a 0.5% solution of trisodium phosphate. Transfer 
to 85% alcohol. 
2. Two days (or less) in the following — 95% ethyl alcohol 280 
ml; distilled water 230 ml; benzol 35 ml; ethyl acetate 95 ml. 
Dried larvae are handled with extreme care, since hairs are more 
likely to get broken in this condition. 
Handling 
The most convenient receptacle for the treatment of larvae is a 
staining dish ( = embryological cup) 41x41x18 mm in outside 
dimensions. Minute specimens, however, are best treated in culture 
slides (= hanging-drop slides). Small specimens are transferred 
with a pipette, larger specimens between the points of forceps (but 
without compression). Or, if one prefers, the larvae may be left in 
the same dish or culture slide; the old reagent is drawn off with a 
pipette and then replaced with the next reagent. 
Cleaning 
The best cleaning reagent is potassium hydroxide solution (10 gm 
KOH in 90 ml water). While still in preservative the larvae are 
punctured with a dissecting needle or minute insect pin on the right 
side to permit the ready penetration of the cleaning solution. The 
number and locations of the punctures and the size of the needle de- 
pend upon the size of the larva. The specimen is left in the cleaning 
solution until all the internal tissues are dissolved and only a trans- 
parent exoskeleton remains. 
If cleaning is not complete by the end of two days, the following 
procedure may prove effective: transfer to 1% hydrochloric acid and 
leave 15 minutes; 15 minutes in 95% alcohol; then leave in KOH 
until clean. Some larvae contain droplets of opaque substances which 
are insoluble in KOH ; these usually disappear later in alcohol or xylol. 
Staining 
The exoskeletons of ant larvae are stained in a very dilute solution 
of acid fuchsin. We use the following formula as a stock solution: 
acid fuchsin 0.1 gm, concentrated hydrochloric acid 1 ml, distilled 
water 1 liter ; a few thymol crystals are added to prevent mold. The 
cleaned exoskeletons are washed in water for 15 minutes and trans- 
ferred to 2 ml of 1% HCL in a staining dish; five drops of the stock 
solution of acid fuchsin are added. The integuments are left in the 
stain for 12 hours. We have experimented with stronger solutions of 
stain for shorter periods but have not been satisfied with the results. 
