732 SUMMARY OF CURRENT RESEARCHES RELATING TO 



hours. They are then quickly imbedded in paraffin, to which ceresin 

 is added. They are cleared with oil of bergamot or cloves. A long 

 stay in alcohol abstracts the colour. By this method the nuclei are 

 stained red, the plasma blue. The three layers of the embryo are 

 clearly differentiated. The ectoderm is a darker blue than the endo- 

 derm. The mesoderm shows the least blue staining, as its cells 

 possess a large (red-stained) nucleus, against which the blue plasma 

 stands out in contrast. 



Mounting Insects without Pressure.* — Mr. K. Gillo describes 

 the process which he uses for this object, and which is a selection 

 and combination of somewhat well-known methods. 



" Let us suppose that the object to be mounted is an ordinary 

 ground-beetle, perhaps 1/2 in. long. The first thing to be done is to 

 steep it in liquor potassae (full strength), and for this purpose I use 

 a test-tube. When the solution becomes dark-coloured, it must be 

 poured away and fresh added. After being in this for ten days or a 

 fortnight, the insect must be transferred to water in a tea-saucer (dis- 

 tilled or soft water should be used), and whilst holding it steady 

 with a camel's-hair brush, gently squeeze the body with another, 

 giving the brush at the same time a kind of rolling motion, thus 

 driving the contents of the abdomen towards the anus, from which it 

 will presently be discharged. The beetle should now be removed 

 to clean water, and left for an hour or so, when the squeezing pro- 

 cess with the two brushes must be repeated as before, when more of 

 the abdominal contents will be ejected. Again place the insect in 

 clean water, and in this way, by several soakings and squeezings, 

 the whole of the contents of the viscera will be removed without the 

 least injury to any of the internal organs. 



Throughout this process, however, the insect will be seen to be 

 as opaque as it was at first. It is, therefore, necessary to bleach it ; 

 and to effect this it must be placed, until sufficiently transparent, 

 which may take a week or more, in the following solution : — A 

 saturated solution of chlorate of potash, to which is added ten or 

 twenty drops or more of strong hydrochloric acid to each ounce of 

 solution. A shallow but large -mouthed corked bottle is best for 

 this purpose. The chlorine, which is slowly liberated in the solu- 

 tion, attacks the chitine, and thus gradually bleaches it and renders 

 it transparent. 



It is now necessary to wash all this solution out of the insect, 

 which is best accomplished by placing it in a small pomatum pot 

 filled with distilled water, and after an hour or so to change the water, 

 repeating the process four or five times." 



" For the next part of the process, a nest of china saucers or 

 palettes, such as are used by water-colour artists (these fit sufficiently 

 accurately one on the other to hold spirit for a day or two without its 

 evaporating), will be required. In an empty palette place the insect 

 on its back, and arrange its legs in the positions they are intended 

 to retain when finished. Now gently pour methylated spirit over it, 



* Journ. of Microscopy, iv. (1885) pp. 151-4. 



