686 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



to an extent equal to the thickness of the section, and is thrown above and 

 a little behind the edge of the knife (fig. 197), so that the section is pre- 

 vented from rolling as it slides upon the knife. When the knife is pushed 

 back preparatory to making the next section, the rod rolls over the prepara- 

 tion, and in consequence of the play of its axis, is kept free from the edge 

 of the knife (fig. 198). The section does not stick to the rod as is the case 

 in Jung's section- smoother. 



Extemporized Section-smoother.* — Dr. W. C. Borden has invented a 

 device for preventing sections imbedded in paraffin from curling. It consists 

 of a bent glass tube, one end of which is passed through a hole in the table 

 and into the other is fitted a camel's-hair brush. For most sections a round 

 brush with long hairs is the most suitable, but for large sections a flat 

 brush is to be preferred. The brush is to be so arranged that it lies lightly 

 yet closely on the surface cif the object to bo cut. The thinnest and most 

 delicate sections are not injured by this method and as the harder paraffins 

 allow the thinnest sections to be cut, great success is obtainable by the 

 combination of this flattener and hard paraffin. 



Making Sections of Injected Lun^.j — Mr. A. J. Doherty injects the 

 lung in situ through the right ventricle with a stiff but freely flowing 

 carmine-gelatin mass (Carter s formula), care being taken to throw the mass 

 in slowly and with a uniform pressure, and not to over distend the vessels, 

 either by injecting too rapidly or for too long a time. When properly filled 

 the pulmonary arteries and veins are ligatured, the lungs are removed 

 from the body, and are then distended with 90 per cent, spirit injected 

 through the trachea, which is afterwards to be closed with a clip or bull- 

 nose forceps. The lungs are then weighted with lead and placed in a 

 quantity of 90 per cent, alcohol. In twenty-four hours they are taken out, 

 the clip is removed from the trachea, and as much alcohol as possible is 

 drained from the organs. After this, they are to be redistended with 90 

 per cent, alcohol and placed in a fresh quantity of spirits of that grade as 

 before. This process is to be repeated on the fifth and tenth days, and at 

 the end of a month the lungs will be found to be hardened without being 

 in the slightest degree collapsed. Cut from one of the lungs, preferably 

 at the root and transversely across a bronchns, a piece, say 1/2 in. square 

 and 1/4 in. thick ; transfer it to a glass beaker half filled with methylated 

 chloroform, place the beaker in a water-bath and heat to 100° P. Shake 

 the vessel occasionally to facilitate the saturation of the tissue with the 

 chloroform, and in half-an-hour, add very gradually (i. e. in small pieces, 

 one after the other) about 50 per cent, of paraffin. Keep the lung in this 

 mixture for one hour, and then transfer to a bath of pure paraffin, kept for 

 two hours at 3^ F. above its melting-point. The tissue will then be 

 thoroughly infiltrated with the paraffin and beautiful sections can be made 

 with a hand microtome and a sharp razor. The sections are passed 

 through three consecutive changes of warm temperature, and finally are 

 mounted in balsam and benzole, 



Gboult, p. — Le nouveau Microtome a levier. (The new lever microtome — Hansen's.) 

 [Constnicted generally on the Thoma plan, its characteristics being the use of ^ 

 lever and the arrangement for cutting either dry or immersion. The object- 

 holder is connected with the short arm of a lever, the arms of which are as 

 1 to 5. At each complete turn the micrometer-screw on the right, which 

 acts on the long end of the lever, rises or falls 0-5 mm., so that the object- 

 holder is moved 0-1 mm. Each of the fifty teeth of the head of the screw 



Tiie Micrr.B'ope, vii. (1887) pp. 97-8 (1 fig.). t Ihi'l., pp. 101-2. 



