G70 SUMMARY OF CUTIRENT RESEAUCnES RELATINQ TO 



ndaptcil to tliis inicrotomo an adjunct which is intended to obviate the 

 defect in this instrument of not beiii<^ able to alter the position of the 

 object in an easy way. Instead of the tube in which the object is fixed 

 with parafliu, the author devised the apparatus shown in figs. 110 and HI. 

 This consists of a copper tube which tits over the main piece, and carries 

 two parallel semicircular rings. Along these half rings runs a steel 

 block, wliich by means of a binding-screw can be fixed at any point 

 of their circuit. The block carries the small movable cylinder which 

 takes the place of the English contrivance. In use the semicircular 

 rin"s are placed horizontally, and by combination of tbe movement 

 along the rings with that of the cylinder about its own axis, the prepara- 

 tion is moved in all directions. But on account of the construction of 

 the microtome, this movement is cramped, and only a turn of 60° instead 

 of 90° is possible. This amount, however, suffices for most cases. 



Inexpensive Section-smoother.* — Fig. 112 shows a device for pre- 

 venting the curling of paraffin sections, which Mr. H. C. Bimipus 

 considers is extremely simple and easily made. After cutting off' the 

 head and point of au ordinary brass pin, fix it parallel to the edge of 



Fig. 112. 



the knife by pressing its ends into two small pellets of beeswax. The 

 proper elevation is easily determined by testing on the waste paraffin 

 before the object is reached. The pin can only be used with the trans- 

 verse knife. With the knife set obliquely, a piece of drawn wire will 

 serve the same purpose. 



Preparing Long Series of Sections with Celloidin.f — The pro- 

 cedure which Dr. J. Apathy advocates very warmly consists in 

 dehydrating the surface of the celloidin block immediately previous to 

 and during the act of sectioning and removing the section to a strip of 

 paper kept moist with bergamot oil. The method in detail is as follows : — 



After fixation by any method, and hardening in spirit, the preparation 

 is passed into absolute alcohol, and when imbedded in celloidin kept in 

 80 per cent, alcohol. 



Staining is done in toto by the hsematoxylin and chromic acid method. 

 The strength of the chromic acid salt (mono- or bichromate of potash) is 

 1/2 to 1 per cent., and this, frequently renewed, is allowed to act for not 

 more than one hour. The hsematoxylin solution is 1/2 per cent., and 

 allowed to act for ten minutes to one hour, according to size of object. 

 The object is then washed, and next transferred to spirit, first 70 per 

 cent., then absolute. The imbedding then follows, and when cutting, in 

 the right hand are held a camel's-hair brush and a needle, while this 

 hand also works the microtome. In the left is held a strip of tracing 

 paper, which is at the same time flexible and stiff". The paper strip is 

 about as broad as the slide and thrice as long as the cover-glass. The 



* Amor. Naturalist, xxii. (1888) p. 382 (1 fig.), 

 t I^IT. Zool. Station Ntapol, vii. (1887) j-p. 742-8. 



