IMBEDDING METHODS. 169 



Leipzig- Gohlis. A description and figures of this instrument 

 will be found in Zeit. f. wiss. Mik., ix, 2, 1892, p. 176. It is 

 worked on the sewing-machine principle : the knife is fixed 

 as in the Cambridge instrument, and the object is made to 

 impinge on it by means of a rotary motion given to a wheel 

 by the hand, and converted by a crank and slide lever into _a 

 vertical one given to a slide carrying the object. This micro- 

 tome cuts with very great rapidity, and those who have worked 

 with it speak very highly of it. I have not tried it myself, 

 but make no doubt the recommendation is justified, though, 

 looking to the construction of the slide, I doubt whether it 

 will afford sections quite so true as those given by a carefully 

 handled Becker. The object-holder does not appear to be so 

 scientifically constructed as the Naples one. Like the Cam- 

 bridge instrument, this microtome is only adapted for paraffin 

 work, and for this reason and the others stated above I do 

 not feel satisfied that it should be preferred to the Becker or 

 Thoma by those who have to be content with a single 

 instrument. 



272. Imbedding Methods. The beautiful processes known 

 as Imbedding Methods are employed for a twofold end. 

 Firstly, they enable us to surround an object, too small or 

 too delicate to be firmly held by the fingers or by any instru- 

 ment, with some plastic substance that will support it on all 

 sides with firmness but without injurious pressure, so that by 

 cutting sections through the composite body thus formed, the 

 included object may be cut into sufficiently thin slices with- 

 out distortion. Secondly, they enable us to fill out with the 

 imbedding mass the natural cavities of the object, so that 

 their lining membranes or other structures contained in them 

 may be duly cut in situ ; and, further, they enable us to 

 surround with the supporting mass not only each individual 

 organ or part of any organ that may be present in the 

 interior of the object, but each separate cell or other anato- 

 mical element, thus giving to the tissues a consistency they 

 could not otherwise possess, and ensuring that in the thin 

 slices cut from the mass all the details of structure will precisely 

 retain their natural relations of position. Such a process of 

 imbedding is at the same time practically a process of harden- 

 ing in so far as it gives to tissues a degree of firmness that 



