166 SUMMARY OF CURRENT RESEARCHES RELATING TO 



in the above method, may be removed by using a hot bath on the 

 table of the Microscope. This bath should be a box of convenient 

 size (not over 2 cm. high), with top and bottom of glass, with an 

 opening at one end for filling with hot water, and another at the 

 opposite end provided with a rubber tube and clamp, for drawing off 

 the water as soon as the object has been arranged. 



Prevention of Bubbles.* — After the imbedding process has been 

 carried thus far, there is still another danger to be carefully guarded 

 against. If the box is left to cool slowly in the air, bubbles are very 

 likely to appear in the paraffin, which will prove a serious obstacle 

 in cutting. Profiting by Caldwell's suggestion, to cool the box in 

 water, one may avoid all such inconveniences. As soon as the 

 paraffin cools around the object, so that its position is secured, the 

 box should be held in a vessel of cold water, first at the surface (until 

 the paraffin has set), then fully submerged. In this way the 

 paraffin is quickly cooled sufficiently for removal from the box, 

 which may then be used for imbedding a second object. A dozen 

 objects may be thus imbedded in a very short time. If the box is. 

 plunged below the surface of the water before the paraffin has become 

 rigid, holes will arise in the mass and fill with water. 



Bulloch's Combination Microtome. — Since the description of 

 this microtome was published, it has been further improved. The 

 attachment for holding the knife consists of two discs, and when 

 placed in position at zero, which is indicated by a spring stop, 

 are 4/10 in. thick. Each disc is 2 in. in diameter and in the 

 form of a wedge. The lower disc is divided into 25 parts, and 

 by the proper position of each wedge any inclination or adjustment 

 can be given to the knife. The periphery of the elevating wheel 

 has a rachet with feeding attachment, but the adjustment for gradu- 

 ating the amount of elevation is on the block which carries the 

 knife, and is worked by means of a sliding arm-piece, and can be 

 gauged from one to twenty teeth, or 0*005 to O'l mm. By this 

 arrangement the knife-carrier can be used on the full length of the 

 bed at any adjustment of the feeding attachment. A ribbon carrier 

 has also been attached. 



Improved Roy Microtome .f — Figs. 42 and 43 show the Eoy 

 microtome as improved by M. C. Verick, from suggestions by Prof. 

 L. Malassez. 



The special advantages presented by this instrument are that it 

 cuts under water or spirit, and that the sections can be made of 

 almost any desired thickness and in any direction. It is specially 

 adapted for freezing, but can of course be used in the ordinary manner. 

 In facility of management, rapidity of movement and sureness, it is 

 claimed to be superior to all microtomes, and only yields to the 

 Eivet microtome for extreme delicacy of sections. 



The object to be cut is fixed in a metal tube fitted with a special 

 but simple arrangement (not shown in the fig.), or if too soft to be 



* Amer. Natural., xix. (188.5) pp. 1248-9. 



t Trav. Laborat. d'Histol. College de France, 1884(1885) pp. 191-206 (3 figs.). 



