THE ADAPTATIONS OF AQUATIC INSECTS. 743 



round. Wash away the excess of glycerine with some water, and dry the 

 side with a soft cloth. When quite dry, apply a ring of cement, and when 

 this has dried, add another coat of black shellac cement. The processes above 

 refer to the study of the external parts of insects ; all the soft tissues and 

 internal organs will, of course, have been destroyed by the potash. Soft 

 internal organs must be dissected out of the specimen under water 





