*Williams’ ice freezing microtome* (fig. 6). This consists of a round mahogany water-tight box provided with an exit tube below, and covered with a strong plate glass lid. Firmly fixed in the centre of the floor of the box is a stout brass pillar surmounted by a brass disc which fits into a hole in the centre of the glass lid, so that its surface is on a level with that of the lid. [Illustration: Fig. 6.--Williams’ Ice Freezing Microtome, with Swift’s plough.] To use it, the box is filled with alternate layers of pounded ice and salt; the lid is then put on and fixed by means of a lateral screw. The tissue to be frozen is gently removed from the gum and placed on the brass disc and plenty of gum painted round it. It should then be covered with a tin cap for a few minutes until frozen. Sections are made with a Swift’s Plough (p. 44). [Illustration: Fig. 7.--Schanze Microtome (see text).] *Schanze microtome* (fig. 7) is the pattern used in the Leipsic laboratories. It consists of a heavy iron frame with a large base. The knife is carried in a clamp which slides along the full length of the instrument, gliding upon two smooth plates of iron which are arranged at an angle to one another. The knife must be moved very steadily and gently, as when using a long blade vibrations are easily set up which prevent good sections being obtained. The surfaces of contact must be kept scrupulously free from dust, and lubricated with equal parts of olive oil and castor oil. There are several object holders, which can be removed and interchanged, one connected with an ether spray apparatus, another suitable for holding an object embedded in paraffin, and a third for grasping an object embedded in celloidin. When celloidin is employed, a specially long knife must be used, and it must be fixed very obliquely in the clamp. The object holder is raised by a fine screw worked by a large brass toothed wheel. There is a ratchet arrangement, by which the object may be raised automatically any desired distance, after each stroke of the knife. It gives most satisfactory results with celloidin and paraffin. (Messrs. R. and J. Beck are the agents). Its cost is about £5. *Becker’s microtome* is made on exactly the same principles as the Schanze. The modifications are that the carrier glides on glass plates instead of iron ones, and that instead of the whole surface of the carrier being in contact with the plates, there are a few smooth ivory buttons only. Friction is thus reduced to a minimum, and very uniform sections can be obtained. The price is the same as that of the Schanze. Frazer has introduced a “student’s sliding microtome” on the same principle as the Schanze which costs about £3.