•-.'02 The Microscope. 



■where it should remain several days, until all the appearance of 

 water about the insect is removed. This may be facilitated by 

 occasionally opening the slips of glass and brushing the object. 

 The longer it remains in turpentine the more transparent it will 

 become, and in that respect may go too far for the best effect. 

 This process may be hastened, and to great advantage with many 

 objects, by heating the turpentine during the operation, by placing 

 a vessel containing the object in contact with a cau filled with 

 boiling water. For many purposes in microscopical work, a can 

 one foot long, three inches thick and six inches wide, with its nozzle 

 on one of its broad sides at the end, will be found useful in fur- 

 nishing a moderately hot surface. In using, it may be placed on a 

 small box with one end of the can projecting over an alcohol lamp, 

 or Bimsen burner, by which the water in the can is heated. Care 

 should be taken to cover the turpentine, to prevent its fumes from 

 coming in contact with the flame. A tin cover of a candy -jar will 

 serve. From the turpentine the insect, removed from the glass 

 slips, should be put in oil of cloves, where it may remain for not 

 less than one day, until wanted for mounting. Hardened by the 

 alcohol, the parts will not readily change position with the excep- 

 tion of the membraneous wings, which all through the process 

 must be managed with great care. 



The most delicate of insect wings will usually become so soft- 

 ened by the liquor potass?e as to resist the most careful endeavor at 

 arrangement. 



The principle involved, in passing the object through the vari- 

 ous fluids, is that each is miscible with the succeeding one, and the 

 last with Canada balsam, its final medimn in mounting. The alcohol 

 hardens the tissues, on which the oil of cloves and turpentine act as 

 clearing agents, making the insect transparent by their high index of 

 refraction. 



Chicago, III. 



THE MICROSCOPICAL EXAMINATION OF UEINARY 

 DEPOSITS. 



SECOND PAPER. 



C. G. JENNINGS, M. D. 



Perfectly normal urine at the time of evacuation, and for a 

 variable period after, is of such a chemical composition that all of 

 its constituents are held in solution. After a few hours' exposure, 

 however, microl)es introduced from the air induce changes in com- 

 position which cause the precipitation of certain compounds. 



