125 



bles will not be fixed. The use of heat as suggested in a 

 later note may expel the air. 



It is our practice to divide our material into at least two 

 similar lots, three or even four if there are plenty of speci- 

 mens, and to use a different fixing agent for each of these 

 lots. For one lot use a sublimate solution, for another a 

 chromic acid solution, and so on. This not only gives a 

 variety of fixation, but insures against total loss in the event 

 of accident to one of the lots. 



Boiling water. — Drop the live insects into boiling water, 

 or put them into a glass beaker and pour boiling water over 

 them. Leave the specimens in the hot water, without further 

 heating it, for two to five minutes. Then remove to 30^ 

 alcohol for three hours, then to 50^ alcohol for three hours, 

 then to io<fo alcohol for twelve hours, finally into 85^ alcohol 

 for keeping. Or the insects may be killed in hot water and 

 then removed to any one of the fixing agents described in 

 the following paragraphs. This is probably the best way of 

 handling whole insects. The method of primarily fixing by 

 boiling water is especially valuable for eggs and pupae, which, 

 owing to the impervious character of their chitin-armor, can 

 hardly be fixed in any other way, but we find that it gives 

 excellent results in almost all general work. 



Picro-aceto-stiblimate . — This useful fixing agent is made by 

 taking of a cold saturated solution of picric acid in 70^1^ alco- 

 hol, one part ; of hot saturated aqueous solution of corrosive 

 sublimate, one part; and a few drops (^ to i«^) of glacial 

 acetic acid. The fresh tissue or live insect should be dropped 

 into this fluid and allowed to remain for from twelve to 

 twenty-four hours (incline toward the longer time). Remove 

 to 705^ alcohol for twenty-four hours. (The alcohol will 

 slowly remove the picric acid, and should be changed two or 

 three times. If warm alcohol is used the removal of picric 

 'icid will be more speedily accomplished.) Then remove to 



