196 HELEN L. M. PJXELL-GOODRICH. 



off in a lump with any hairs of the thorax that it touched. 

 Attempts were made to tinge the wings by applying a dye 

 ■dissolved in water, alcohol, chloroform or ether, but no 

 penetration could be effected. 



The least unsatisfactory method of marking in some ways 

 is to clip the tip of one or more wings. This does not 

 interfere with flight so long as only the very tip is removed. 

 By clipping different combinations of the four wings any 

 number at a time (2*-l), i.e. fifteen different dates of hatch- 

 ing could be indicated. Tlie drawback to this method is, of 

 course, the diflBculty in recognising a clipped bee except at 

 very close quarters. 



For keeping bees under special observation I use large 

 glass bell-jars in which they can take short flights, and will 

 sometimes live for three or four weeks. Each jar is provided 

 with a large piece of crumpled paper in which the bees can 

 hide from the light, and honey, syrup or candy and pollen 

 are supplied at intervals. By adding various drugs to the 

 food it is easy to test their action, but on the whole wasps 

 •or bumble-bees are better for feeding experiments since they 

 live longer in captivity. 



Technique. 



After some preliminary experiments the brains were found 

 to be best fixed for the routine study of nerve-cells in the 

 following way : The whole head is cut from a living bee, 

 after subduing with chloroform, if necessary. The upper 

 part of the chitin (just above the three simple eyes) is quickly 



> Since writing this I have heard from Mr. BuUamore that at the 

 ■Cambridge Institute of Bee-keeping they have added to the pigment 

 used some of the preparation known as "new skin,'' and in this way 

 managed to distinguish hees for three or four weeks. Certainly the 

 addition of the celloidin solution is an improvement, appearing to give 

 -elasticity and so prevent the pigment from coming ofE so quickly. 

 However, even this has a tendency to peel off and bring the thoracic 

 hairs with it, so that I am afraid it may still be diflScuIt to recognise 

 bees after four or more weeks, and these are the ages at which specimens 

 Are now required for study. 



