1899J MICROSCOPICAL JOURNAL. 197 



mCROSCOPICAL APPARATUS. 



Nosepiece. — The inner screw on Reichert's and Leitz's 

 objectives is that of the Hartnack stand. By taking- out 

 the stop, these objectives can be used on any old Hartnack 

 stand without the necessity for an adapter. I do not think 

 this is g-enerally known. — J. B. Nias. 



Fixing and Hardening Apparatus. — An ing-enious West- 

 erner has cut up g-lass tubing- into 3 centimetre lengths 

 and made little buckets of them by turning out rims while 

 melted. Over this a cloth bottom is made fast by tying 

 and to the other end is attached a suspender for handling 

 it. In the bucket, place small sporanges, flower buds and 

 other vegetable tissues to be hardened. Immerse the 

 bucket in the hardening liquid. 



Critical Illumination. — To secure this, place the instru- 

 ment horizontal. Project the thin edge of a flame along- 

 the optical axis of the condenser, so that the image viewed 

 with a one-inch objective shall be sharply defined in the 

 same field of view as that occupied by the objects when 

 under observation. Then substitute for the one-inch a six- 

 teenth, a twenty-fifth, or a fiftieth. With slight readjust- 

 ment of the achromatic condenser, the field of view will be 

 brilliantly illuminated and the most flagellate organisms 

 defined with great sharpness. 



Microtome Knife. — Professor T. D. Briscoe of Mari- 

 etta College has made an addition to his student microtome 

 to offset two difficulties. The pressure of one's hand on 

 the knife block caused the knife to change the thickness of 

 the slice being cut ; and second, in case the block of tissue 

 presents structure harder in one part than another, the 

 knife could not be cartied steadily thr6ugh the whole of 

 a section. The knife block should be pulled in a perfectly 

 horizontal direction, with no chance of any greater or lesser 

 pressure downwards on the way, and by adding a lever 

 with the power-arm five or six times as long as the arm at- 

 tached to the knife-block a steady motion can be secured. 



Light. — The position of the carbon points in an electric 



