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.MKTIIOD AND .MAT KIM A I, 



Tin- method of microdissection has been greatly improved with the 

 use ..!' glass needles manipulated in a three-movement holder intro- 

 din-cd several years ago liy Dr. .M. A. I'.arher and later extensively 

 employed In Kite and ( 'hamb. rs (1!)1l_M. Kite 1!M:!,/ and &), Cham- 

 bers f1!H4. 1!)1.">. 1017. b. and 1!I1S) and Seifri/ (1918). Tlic 

 technique used liy these investigators makes possible the dissection 

 and observation of ova. spennato/.oa. fresh tissues and Protozoa under 

 the highest magnification of the microscope. A detailed description 

 of the method is -riven by Barber (10141 which has been elaborated 

 by Chambers i 1H1.~>. 101*>. T have made use of the principal features 

 of this method in these studies on Kit/iluto; jiniillii, 



The efficiency of the liarber instrument is indeed remarkable. Con- 

 siderable experience was found necessary for drawing the finer and 

 m"st serviceable needles, but their manipulation in the three-movement 

 holder is a comparatively simple matter. One learns the adjustment 

 of the screws controlling the needle almost as readily as the operation 

 of a mechanical sta-re. After some practice the facility with which 

 the apparatus may be manipulated and the feats thus made possible 

 with a pi ass needle arc rather surprising. 



Mnixl i Itimilii rs. Two forms of moist chambers have been success- 

 fully employed. A Mausch and Lomb monocular microscope havin.-r a 

 rotary staire was first used. For this sta<re a convenient round moist 

 chamber was devised as follows: The base of a heavy, extremely 

 shallow petri dish, in diameter slightly less than that of the rotary 

 stage, was fastened upon the latter by means of two brass posts 20mm. 

 long sen-wed into the clip holes of the stage. The upper ends of these 

 posts firmly supported the top of a large stender dish, this top or roof 

 having a diameter eijiial to that of the bottom or floor. It will lie 

 observed that both roof and floor were thus securely fastened to the 

 rotary stage. On the other hand, the wall of the moist chamber, made 

 from the upper portion of the stender dish mentioned above, was 

 solidly attached by two brass arms to the shank of the microscope and 

 was of such height as to permit free movement of the roof and floor. 

 A hole throuirh the wall on the right allows the insertion of the needle 

 into the moist chamber. Also, a circular hole 20 mm. in diameter 



