766 SUMMARY OF CURRENT RESEARCHES RELATING TO 



reduction), quickly transfer the warmed slice (whicli should now be 

 close at hand) to it, while with a little pressure the ' smoothed ' 

 surface is brought into direct contact with that of the glass. Thus 

 let it remain on the table where this is done until the glass feels cold 

 to the touch. 



After this reduce the slice to the thinness of a wafer over a very 

 fine vertical rotating griuding-stone, or on a copper plate with emery 

 powder and water, horizontally. 



Now wash it well in water, and, placing the slide on a piece of 

 buckskin leather spread on the table or on a level sui-face (to keep it 

 from slipping) with the slice uppermost, continue the reduction in 

 water with a piece of very fine siliceous limestone, that may be ob- 

 tained from a statuary of convenient form (that is, one which will 

 admit of the surface of the slice coming into direct and continuous 

 contact with that of the limestone), with which it should be horizon-? 

 tally rubbed until reduced to the required thinness, which must be 

 ascertained by repeatedly transferring the slice to the field of the 

 Microscope with a 1 in. object-glass and high ocular. The nearer 

 this thinness is approached the oftener this transfer should be made, 

 washing the slice by dipping the slide into a bowl of water each time 

 that it is examined. 



When sufficiently reduced, wash the slide as before, and stand it 

 up to drain until the slice is perfectly dry. Then cover with benzol, 

 followed by balsam and thin glass, for preservation and more deliberate 

 examination. 



I make no apology for introducing these remarks, as the ' process,' 

 although open to criticism and improvement, no doubt, answers the 

 purj^ose ; and while inexperienced, I myself should have been very 

 glad of such aid. Dr. Holl suggested to me the use of shellac, whicli 

 is the most valuable hint that I have received." 



Verification of Microscopical Observation.* — This formed the 

 subject of the address of President A. McCalla to the Sixth Annual 

 Meeting (at Chicago) of the American Society of Microscopists. 



After remarks on the practical value of the Microscope and 

 microscopical studies, " the woi:ld at large not being enough aware 

 how great is the debt it owes to microscopic research," the address 

 referred to the danger of a neglect of the painstaking precautions 

 necessary to insure truth and the necessity for careful and laborious 

 investigation into a thousand minutise whose after-importance cannot 

 always be known, the substantiating a phenomenon observed by chance 

 by many a set experiment, the framing an hypothesis to account for 

 the facts observed and testing its truth by a series of observations 

 under many varying conditions. That very popularization of the 

 Microscope which is so encouraging in our day tends to a lack of 

 care in its use. 



" When we reflect, then, on the high order of knowledge and of 

 skill which the scientific use of the Microscope demands it is no 



* 'Chicago Times,' Sth August, 1883, iu advance of Proc. Amer. See. Micr., 

 Ctb Auu. Meeting, 1883. 



