36 T. C. WHITE ON INSECT DISSECTION. 



may be formed out of needles set firmly in wooden handles. They 

 may be of different widths and of various curves — such a needle 

 ground flat and sharpened makes an excellent knife, while some of 

 the needles may be blunt and slightly bent for the purpose of holding 

 the different J3arts down while they are cut, or of separating the 

 organs from the entangling mass of trachea}, with which they are 

 bound to the adjacent structures. 



Another useful auxiliary will be found in the fluid under which 

 you must always carry out your dissection, by increasing the density 

 with glycerine, and varying it according to circumstances, it may be 

 made to support and hold out of the way delicate structures that 

 would be liable to injury or impede the progress of dissection during 

 the operation. 



The other implements necessary are a small square of entomo- 

 logical cork, loaded by insertion in a plate of sheet lead, to which 

 your subject may be fixed. A glass trough, about 1 inch in depth, 

 or even less for some cases, is better than any other I have tried. 



Noav I do not, in this short paper, pretend to give you anything 

 more than the modus operandi I have found useful to myself. I 

 know there are others here who may have further information to im- 

 part relative to their procedure, and to those these few remarks may 

 serve as the text for the subsequent discussion. 



In preparing an insect for dissection, if you intend to examine 

 merely the internal organs, it is better to remove all the external 

 organs as the legs, antennae, &c, of course previously killing the in- 

 sect with chloroform. Then the plan usually recommended is to 

 pin the subject on the loaded cork, and place it in the trough under 

 water. Now this plan is very well in some cases, but I prefer 

 another, which I can recommend as being far more efficacious, and 

 that is while your insect is dry drop upon the part you intend to 

 fix it by, some melted wax and Canada balsam, the same composition 

 that I have before recommended to be used as a cement for cells in 

 dry mounting, only in this case you have to add a little more Canada 

 balsam. You may then drop some more on your loaded cork, and 

 stick your subject on it. There is an advantage about this, which 

 the simple pinning will not afford, and that is you may dissect your 

 subject to the last piece without dragging it off the cork, which very 

 often occurs through the pins on the subject giving way. 



Now having fixed your subject, insert the point of your scissors 

 between any of the abdominal segments at the junction of the tergal 



