14 THE AMERICAN MONTHLY [Jan 



order to get an equal distribution of casts throughout the 

 field, it is necessary to carry a fine needle from the outer 

 margin of the urine to the centre of the medium until the 

 two substances show no tendency to separate, care being 

 taken lest air bubbles are produced. A cover glass is 

 moistened by the breath and then allowed to fall gently 

 ou the specimen. The slightest pressure, or the applica- 

 tion of heat, is usually destructive to casts. The slide is 

 now put in a cool place for a few hours, in order that hard- 

 ening may be complete. A permanent ring of zinc-white 

 has been shown to be of value in the preservation of these 

 specimens. Some illustrative plates were sketched from 

 specimens that had been mounted two years and a half, 

 and show perfectly every feature possessed by casts studied 

 from the same urine after the usual methods employed. — 

 L. N. Boston, M. D., N. Y. Med. Journal. 



Agar-Agar. 



W. W. ALLEGER. 



The preparation of agar by the older methods is well 

 known to be a tedious operation, which consumes much 

 valuable time. The product obtained is seldom, if ever, 

 quite transparent; while not infrequently troublesome 

 precipitates which not only mar the appearance of the 

 medium but render it unsuitable for the finer classes of' 

 work, develop after sterilization. 



The use of powdered agar, which has been in the mar- 

 ket for two or three years, because of its ready solubil- 

 ity, simplifies the process and greatly shortens the time 

 required in the preparation of the medium ; but for some 

 reason, doubtless because of the scant notice which has 

 been given to the matter in the literature, it does not yet 

 seem to have come into general use. To call attention to 

 the powdered form, and report a method for obviating the 

 appearance of secondary precipitates in the tubes.on ster- 



