BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [88] 



expert enougli to remove tlie slide and cool it at just tlie right time, 

 when the scales will have been rendered nearly transparent by the 

 balsam, while the veins remain filled with air. We have done this sat- 

 isfactorily not only with Tortricidfe and Tineidse, but with Noctuids of 

 the size of Aletia and Leucania. The mounts are permanent, and we 

 have some which have remained unchanged since 1880. Prof. 

 Eiley had for some years before this been in the habit of mounting 

 wings in balsam, in which of course the scales cleared after a time." 



Prof. John B. Smith recommends a modification of the Dimmock 

 process of bleaching the wings of Lepidoptera, publishing it in Insect 

 Life, Yol. I, pp. 291, 292, as follows: 



"By the Dimmock process the wings are first acted upon by a sat- 

 urated solution of the chloride of lime, chlorine being, of course, the 

 bleaching agent. Afterward they are washed in water to which hydro- 

 chloric acid has been added, to get rid of the slight deposit of lime. 

 The process is a slow one for thickly scaled, dark-colored insects, and it 

 occurred to me to try a mixture of the chloride and acid, liberating the 

 chlorine gas. The method was absolutely successful, the wings decol- 

 orizing immediately and being ready for the slide within two minutes. 

 In fact, very delicate wings can scarcely be taken out quick enough, 

 and need very little acid. The advantage is the rapidity of work and 

 the certainty of retaining the wings entire, the chloride of lime some- 

 times destroying the membrane in part before the bleaching is com- 

 plete. The disadvantage is the vile smell of the chlorine gas when lib- 

 erated by the combination of the two liquids. For quick work this 

 must be endured, and the beauty and completeness of the result are 

 also advantages to counterbalance the discomfort to the senses." 



For further special directions for mounting, for microscopic purposes, 

 different insects and the different parts of insects, representing both 

 the external chytinous covering and the internal anatomy, the student 

 is referred to special works. 



PKESEEVATION OF ALCOHOLIC SPECIMENS. 



Apparatus and Methods. — The collections of most value, espe- 

 cially to our various agricultural colleges and experiment stations 

 wiU be largely of a biologic and economic character, and the interest 

 attaching to a knowledge of the life history of insects will induce many 

 collectors to build up independent biologic collections. Very much of 

 this biological material will be alcoholic, and though many immature 

 states of insects may be preserved by dry processes, still the bulk must 

 needs be kept in liquid. This material may, when not abundant, be kept 

 with the general systematic collection, but experience has shown that it 

 is better to make a separate biological collection, and this is recommended 

 especially for State institutions where the collections may be expected 

 to attain some considerable proportions. In the case of such collections, 

 it is very desirable to adopt some method of securing the vials in such a 



