144 SUMMARY OF CUERENT RESEARCHES RELATING TO 



The principal advantages to be obtained by tlie use of the 

 Taylor Microtome are, 1st, great economy in the method of freezing, 

 and 2nd, celerity and certainty of freezing. With an expenditure of 

 twenty-five cents the tissues to be operated on can be kept frozen 

 for several hours at a time. Small objects immersed in gum solu- 

 tions are frozen and in condition for cutting in less than one 

 minute." 



A is a revolving plate by which the thickness of the section is 

 regulated, and in the centre of which is an insulated chamber for 

 freezing the tissue. A brass tube enters it on each side. The larger 

 one is the supply tube, communicating with a pail on a bracket above 

 the microtome, whilst to the smaller one is attached a rubber tube, 

 which discharges the cold salt water into a pail j^laced under it. The 

 salt and water liquid, as it passes from the ujiper to the lower pail, 

 is at a temperature of about zero. The water should not be allowed 

 to waste, but should be returned to the first pail for continual use, or 

 as long as it has freezing properties. As a matter of further economy 

 it is necessary to limit the rate of exit of the freezing water. This 

 is regulated by nipping the discharge tube with the spring clothes- 

 pin supplied for the purpose. Should the cold within the chamber 

 be too intense the edge of the knife is liable to be turned and the 

 cutting will be imperfect. "When this occurs the flow of water through 

 the chamber is stopped by using a spring clothes-pin as a clip on the 

 upper tube. In order to regulate the thickness of the tissue to be 

 cut a scale is engraved on the edge of the revolving plate A, which, 

 in conjunction with the pointer e, indicates the thickness of the 

 section. 



Mr. C. P. Lyman, of the Department of Agriculture, writing in 

 strong commendation of the apparatus, says : — " There is no little box 

 that must be kept full of ice and salt and constantly attended to ; 

 neither is there any tiresome bulb to squeeze for a period of any- 

 where from fifteen minutes to two hours, nor the expense and danger 

 attending the general use of ether or rhigolene. The simplicity of 

 the operation of freezing morbid material for sections, now obtainable 

 through the use of this instrument, will, I think, remove from the 

 study of pathology one of its hitherto greatest bugbears, viz. the 

 great labour of preparation of material for section and the difficulty 

 of obtaining good sections of soft tissues unaltered by the various 

 chemical reagents hitherto used for the purpose of hardening 

 them." 



Mounting Media.* — Prof. H. Hoyer has found excellent mount- 

 ing media not only in L. Bach's solution of gum arabic in liquor 

 ammonise aceti, but also in acetate of potash, as well as a third modi- 

 fication with glycerine and chloral. The two former are more 

 particularly suitable for preparations stained with aniline colours, 

 especially bacteria. The latter is suitable for sections hardened in 

 chromic acid, alcohol, &c,, and objects coloured with carmine or 

 hsematoxylin. 



* Biol. Centralbl., ii. (1S82) pp. 23-4. 



