170 



SUMMARY OF CUREENT RESEARCHES RELATING TO 



to act SO that the catch I will take any desired number of teeth by every 

 revolution of the object. The knife moves only during that part of the 

 revolution when the object is not in contact with the knife. The ribbon of 

 sections slides downward from the knife and is caught on a piece of paper 

 placed upon the table. The wheel holding the object, as well as the 

 razor, can be moved so that almost all parts of the edge of the razor can 

 be used. 



The frame-bed of the microtome is made of iron, the screw of steel, and 

 all the rest is brass. Any ordinary microtome knife or razor may be used. 



The machine has been in use at the Johns-Hopkins University at 

 Baltimore, for a year, and gives the greatest satisfaction. It can be used 

 with great rapidity, but so far the best results have been obtained at a 

 rate of not over 100 sections to the minute. The only possible error in 

 a revolving microtome of this kind is theoretical — namely, that owing to 

 the circular motion of the object, each section is part of a hollow cylinder. 

 But in reality, with objects of ordinary size, this error is not apparent, 

 and even under a high magnifying power there is no perceptible difference 

 between sections cut by this microtome and those cut by ordinary slide 

 microtomes. 



Hildebrand's Microtome.* — Dr. H. E. Hildebrand has made several 

 improvements to his " Simple and effective Microtome " already described. "j" 

 On the sides of the object- and knife-carriers excavations with roughish 

 surfaces have been made for the reception of the thumb and first two 

 fingers. The clamp of the knife-carrier is now made of metal and is 

 lighter, and all the metal parts are nickeled. 



Martinotti's Knife-holder for Sliding Microtomes. | — Dr. G. Martinotti 

 has designed a simple clamp (fig. 27) for the purpose of fixing ordinary 

 razors to the carrier of the sliding microtome. 



Fig. 27. 



The arrangement consists of two clamps a and c, which are connected 

 by a ball-and-socket joint h. The long bars of the clamp a are fixed to the 



* Zeitschr. f. Wiss. Mikr., iii. (1886) p. 392. t i^ec this Journal, 1886, p. 886. 



% Zeitsclir. f. Wiss. Mikr., iii. (1886) pp. 300-2 (1 fig.). 



