LEPIDOPTERA. 197 



veins can be rendered more distinct for a few seconds by putting a 

 drop of chloroform on the part of the wing to be examined ; this can 

 be easily done by means of a camel's-hair brush. 



Sometimes it is necessary to remove the scales from a small part 

 of the wing in order to determine the nature of some characteristic; 

 this can be easily done with an artist's sable brush. A very small 

 brush is best for this purpose; and care should be taken not to break 

 the wing. 



The above methods are all that are needed in the majority of 

 cases where the mere determination of an insect is the object. But 

 when a very careful study of the venation of a wing is to be made, 

 it should be bleached and mounted on a card or on a glass slip in 

 order that it may be studied with a compound microscope. The fol- 

 lowing is the method of bleaching wings: — 



1. Remove the wings carefully so as not to break the frenulum if 

 there be one; it is well to remove the patagium first. 



2. Dip the wings in alcohol in order to wet them. 



3. Immerse them for an instant in hydrochloric acid (muriatic acid). 

 Use for this purpose dilute acid, one part acid to nine parts water. 



4. Put them in Labaraque solution with the upper surface of the 

 wings down, and leave there till the color has been removed from the 

 scales. If a wing bleaches slowly, the process can be hastened by 

 dipping it in the dilute acid and returning it to the Labaraque 

 solution from time to time. This solution can be procured of most 

 druggists. It deteriorates if left exposed in strong sunlight. If it 

 cannot be obtained, use an aqueous solution of chloride of lime. 



5. When a wing is bleached put it in alcohol and leave it there till 

 after it floats. This is to wash off the Labaraque solution. The 

 wino- can then be mounted on a card. But it is better to mount it as 

 described below. 



6. Transfer the wing to a clearing mixture, if it is to be mounted 

 in balsam, and leave it there five or ten minutes. This is to remove 

 any water there may be on it. A good clearing mixture can be made 

 by mixing two parts by weight of carbolic-acid crystals and three 

 parts of rectified oil of turpentine. 



7. Put the wing on a glass slip with considerable clearing mixture 

 under it to avoid bubbles ; put Canada balsam on top, and cover with 

 thin glass. In the case of small wings, it is best to transfer them 

 from one solution to another, and to the glass slip by means of a 

 camel's-hair brush. 



Wings bleached and mounted in this way make an important ad- 

 dition to a collection. The slides should be carefully labelled ; and 



