886 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



spring q q'. By working either of these screws, the corresponding 

 frame turns on its axis. 



A micrometer-screw r measuring 10 cm. serves to drive up the 

 object-carrier. Its head t projects some way from the microtome, 

 and may have any diameter. Communication between the front end 

 of the screw and the carrier is obtained by means of a steel cylinder 

 which passes through the opening u in the carrier, and which by 

 means of a binding-screw v can be fixed at any point. The rotation 

 of the screw is rendered audible by a catch x working on the barrel 

 w. The latter has five divisions marking 1/2, 1/3, 1/5, 1/10, and 

 1/50 of a turn, which for corresponding sections gives a thickness of 

 1/40, 1/60, 1/100, 1/200, and 1/1000 mm. 



Hildebrand's simple and effective Microtome.* — Dr. H. E. 

 Hildebrand has devised a microtome of great simplicity and of small 

 cost, and which he says equals in effectiveness any hitherto pro- 

 duced. 



The body of the instrument (fig. 183) is of cast iron, 30 cm. 

 long and 18 cm. broad. The upper aspect shows three surfaces, 



Fig. 183. 



which serve as slide-ways for the knife and object-carriers. The 

 former moves along the upper or horizontal surface ; the latter 

 along the lower one which is sloped. The vertical surface is common 

 to both, and prevents any lateral yielding. All three surfaces are 

 planed perfectly smooth. On the lower part of the inclined plane is 

 a female screw for the reception of a micrometer-screw with a large 

 milled head. When the screw is turned, it pushes the object-carrier 



* Zeitschr. f. Wiss. Mikr., ii. (1885) pp. 313-5 (1 fig.). 



