Three different forms of clamps may be had for these microtomes, and freezing apparatus as well as paraffin tables can also be fitted. The Fixed clamp, No. 128, represented in the figure of the large sliding microtome, serves to clamp the specimen in position and does not allow any further adjustment. The Ball and Socket clamp permits the adjustments of the specimen after it is held in the clamp by means of a ball and socket joint--see figure of No. 129--a set-screw then holds it firmly in position. The Naples clamp permits the accurate adjustment of the specimen at any level, the clamp being supported on two horizontal axes at right angles to each other, the one controlled by rack and pinion, the other by endless screw. The knife-carrier is arranged to hold the Thoma form knives, which are fastened by means of a wing-screw. Other knives require a special holder, such as No. 139. 122. =The Large Sliding Microtome= has a track 42 cm long. Its price with automatic feed attachement, wheel and chain arrangement for the knife carrier, and fixed clamp, without knife =62.--= 123. =The same=, with knife holder for Jung microtome knives =66.--= 124. =The same=, but without the wheel and chain arrangement for the knife carrier =50.--= 125. =Medium size Sliding Microtome=--Track 32 cm long; automatic feed attachement; wheel and chain motion of knife carrier and fixed specimen clamp--without knife =56.--= 126. =The same=, with knife holder for Jung microtome knives =60.--= 127. =The same=, but without wheel and chain motion =44.--= 128. =Fixed Specimen Clamp= =4.--= 129. =Ball and Socket Clamp= =6.--= 130. =Naples Clamp= =12.--= [Illustration: Ball and Socket Clamp No. 129. Naples Clamp No. 130.] 131. =The Support-Microtome= has a track 19 cm long. The knife-carrier slides on a double flanged support and is moved by means of a large knob. The motion is smooth and quick. The specimen is held in a clamp supported on two adjustable axes at right angles to each other, thus permitting its adjustment in any position. The specimen carrier is moved vertically by means of a micrometer screw to which a large disc is attached. This disc is graduated, each degree representing a motion of the specimen carrier of 0,005 mm. The price of this microtome with knifeholder No. 139, without box or knife is =34.--= [Illustration: Support-Microtome No. 131.]