1052 SUMMARY OF CURRENT RESEARCHES RELATING TO 



lower end being screwed into a brass base E. To its upper end is fastened 

 by two bayonet-catches a brass plate F, on which the tissue to be cut is 

 placed. Inside the cylinder D, and rising from the base E, is an ordinary 

 spray, the air and ether being supplied through tubes G and H, passing 

 outside, through the base. There is also an opening in the floor of the 

 chamber communicating with the tube I, to allow the overflow of ether in 

 case of any accumulation inside the cylinder ; any such overflow may be 

 returned by the tube to the ether supply bottle K. The freezing chamber 

 is secured to the top of the micrometer-screw arrangement Z, which is of 

 the simplest form, but has a perfectly smooth and regular motion. The 

 nut is divided to indicate a section ■ 01 mm. in thickness, but half this 

 thickness can be cut without difficulty. 



The method of using the microtome is very simple. The slide and 

 block D having been carefully rubbed clean and well oiled, the razor is 

 clamped at any desired angle, the bottle K is filled with ether (good dry 

 methylated ether answers perfectly), and the piece of tissue to be cut having 

 been previously saturated with thick gum solution^ is placed upon the 

 plate F, and the spray which plays upon the under surface of the plate P 

 set working by the hand-pump M ; in a short time the tissue will be frozen 

 quite through, and if a number of sections are required, an occasional 

 stroke or two of the pump will keep the gum in proper condition for 

 cutting. The sections are easily cut, as in other microtomes of this class,^ 

 by alternate movements of the screw Z and stroke of the razor. 



The instrument may also be used for cutting tissue imbedded in paraffin 

 or other mass, the object to be cut being secured in position, either by 

 being gently heated at its under surface and pressed on the plate F, to which 

 it firmly adheres on cooling, or by a simple clamping arrangement, which 

 can be substituted for the freezing-chamber. When used in this way large 

 numbers of sections may be cut in series by attaching to the razor a light 

 support to receive the sections as they are cut. 



Paoletti's Automatic Microtome.* — Sig. E, Paoletti has invented an 

 automatic microtome, which is said to answer perfectly. To a rectangular 

 vertical upright are adapted two guides, between which the object-carrier 

 moves vertically. The carrier is fitted with a clamp, movable in all 

 directions. A micrometer screw, to which is fixed a toothed wheel, moves 

 the carrier vertically upwards. Another wheel fixed to the upper end of a 

 vertical plate is moved with this in a horizontal plane by a movement of 

 rotation, which is transmitted to it by a lever. From the periphery of the 

 wheel projects a vertical tooth, which, acting excentrically, displaces with 

 a to-and-fro horizontal movement a knife-carrier, the level of which is a 

 little higher than that of the clamp containing the preparation. At the 

 lowest part of the plate is another tooth, which, as the instrument works, 

 meets at intervals of about half the circumference the teeth of the cogwheel, 

 and by locking with these imparts to the screw a displacement which serves 

 to raise the object-carrier. Now in one complete turn of the plate the 

 movement of the knife takes place in one half, the raising of the specimen 

 in the other half. The tooth which causes the cogwheel to revolve can be 

 approximated to or removed from the latter by a milled head, and thus 

 displace it by a greater or less segment, according to the thickness desired 

 to be given to the sections. According to the distance of the tooth from 

 the cogwheel, the latter can be displaced by a fifth to a twenty-seventh of 

 the circumference, and thus a thickness varying from • 1 to • 02 mm. can 

 be given to the sections. 



* Atti Soc. Tosc. Sci. Nat.— Proc. Verb., v. (1887) pp. 250-L 



