lo Collection and Prepa7'ation. 



microscope. For the former purpose, small pieces of the leaves 

 or branches with the attached insects may be pinned or gummed 

 upon cards, and arranged in the drawers of a cabinet, like any 

 other collection of insects. Such an arrangement will be found 

 useful for rough comparison of specimens. 



But for accurate determination a careful microscopical examina- 

 tion is absolutely necessary. There are many species that it would 

 be quite impossible to separate by their external characters alone. 

 A rather more elaborate preparation is necessary to exhibit the 

 structural details. The specimen to be examined has first to be 

 boiled for a few minutes in some strong alkali, such as liquor 

 potassse, over a spirit-lamp, the time to depend upon the size of 

 the object. As soon as the specimen begins to look clear and 

 skeletonised, the boiling should cease. The process will be assisted 

 by previously making a small opening in the body of the insect^ 

 to allow of the soft parts being expelled. Large species such as 

 Walkeriana, Icerya, &c., can be boiled in a wide test-tube or 

 beaker ; for smaller insects I find it more convenient to use a 

 deep watch-glass, from which they can afterwards be more easily 

 removed. This boiling process will also serve to restore the 

 shrivelled specimen to its normal form and dimensions. From 

 the potash they should be shifted to a vessel (another watch-glass) 

 containing distilled water, the specimens being lifted with the 

 flattened point of a piece of thin wire (a feather or brush would 

 be rapidly destroyed by the caustic action of the potash). Here 

 they may remain for an hour or more, by which time the potash 

 will have been removed together with more of the decomposed 

 contents of the body. Next lift the insect carefully on to a 

 glass slide, depositing it in a drop of alcohol (or rectified spirits 

 of wine), arrange the parts conveniently for examination, using a 

 fine camel's-hair brush or snipe's feather ; put a drop of weak 

 glycerine on a thin cover-glass, and lower this gently on to the 

 object, which is now ready for a further examination. I find 

 glycerine more suitable than alcohol, as the latter evaporates so 

 rapidly, while the former will remain for days or weeks without 

 appreciable reduction in quantity, so that specimens may be kept 

 under observation for some time without further treatment. With 

 this medium all the minute details of structure can usually be 

 distinguished, and carefully enlarged drawings of the limbs, 

 spinnerets, marginal processes, &c., should now be made. I find 

 the I, \, and J inch micro-objectives the most convenient for the 



