1880.] 



MICEOSCOPICAL JOURNAL. 



89 



stem-rod. Unscrew this lens, and 

 put in its place a piece of cork, 

 through which a needle passes at a 

 right-angle to the stem. It is well 

 to have two or three pieces of cork 

 fitted with needles having different 

 points ; one, for instance, may have 

 a human hair projecting slightly 

 beyond its point, the hair being 

 kept in place by winding with fine 

 thread and coating witli gnm ; an- 

 other may have a fiat point, made 

 by breaking off and grinding the 

 fractured end; other forms will 

 suggest themselves as experience 

 may determine. The ball-and- 

 socket joint should be clamped or 

 wedged, so as to move quite stifily. 

 Bring the point of the needle into 

 view under the objective, and it 

 may be made to touch the slide, or be 

 lifted away from it by simply turn- 

 ing the stem-rod. Objects which 

 are seen to adhere to the needle 

 are lifted at once and another 

 slide, slightly moistened by breath- 

 ing on it, may be substituted for 

 the one on the stage, to which the 

 objects may be made to adhere at 

 any desired point, by turning the 

 stem-rod as before. By moving the 

 mechanical stage while the point of 

 the needle is in contact with the 

 slide, objects may be puslied wher- 

 ever desired on the slide. In this 

 case it is a decided advantage that 

 both needle and object remain 

 within view, however the stage is 

 moved. Thus dirt may be scraped 

 away with the greatest ease. 



It is evident that such a contri- 

 vance, consisting essentially of a 

 ball-and-socket joint, and a sliding 

 stem with a button attached to the 

 latter, so that it may be readily 

 turned, might be fitted to the 

 stand of an ordinary bull's-eye con- 

 denser, and thus become available 

 for use with any microscope-stand 

 whatever. 



M. A. Yeedee. 



The Objectives which Aiford the 



most Accurate Knowledge 



of Histology. 



BY A. A. BEAGDON. 



After years of study with the 

 microscope, having commenced 

 with one of the lowest grades of 

 the instrument, and gradually try- 

 ing to improve my tools, and at the 

 same time to keep informed in re- 

 gard to modern improvements by 

 carefully perusing what has been 

 written upon the subject ; and hav- 

 ing, in the course of those years, 

 used various grades of objectives ; 

 I trust I may venture to express 

 myself as to what, in my opinion, 

 are the best lenses for histological 

 studies ; hoping, that by so doing, 

 I may enable some younger student 

 than myself, who is just commenc- 

 ing the study, to make a short cut 

 to success, and not travel tlie long 

 road of experience, as I have, to 

 arrive at my present conviction, 

 as regards the 'best objectives for 

 my study. 



In order for the student who 

 truly desires to obtain accurate 

 knowledge of organic tissues, as 

 well as to search out the hidden 

 mysteries of biological science with 

 success, several things are impera- 

 tively necessary, among which, for 

 the former study, two are very im- 

 portant : 



First. — Some method of making 

 perfect sections. 



As an aid in making such sections 

 and mounting them, the student 

 cannot easily find more complete 

 and practical instruction than that 



fiven in a series of articles by Dr. 

 . J. Woodward in The Lens., Vol. 

 I, 1872, or, in a series of articles 

 by Dr. Carl Seller, published in the 

 Am. Quar. M. Journal for Janu- 

 ary and April, 1879. 



The knife-carrier described in 

 the latter article can be used with 



