780 SEC. 18. BIOLGOY. 



3 634: a. Microtome. Dr Gaper, Marburg. 



This adaptation of the large Guddan microtome has been designed for em- 

 bedding. The object and the enclosing mass being held fast by the screw at 

 the top of the piston, the often condemned defect of repeatedly melting down 

 in the case of large objects is avoided. The cylinder is slightly narrowed 

 towards the top, in order that the object may more surely resist the knife 

 which is guided by the hand on a polished steel surface. The instrument 

 can be employed with any suitable liquid in the bowl, which can afterwards be 

 drawn off through a gutta-percha tube, and the object being slightly screwed 

 down, may be covered with a glass slide as a protection against drying up. 

 In this way operations on the same object on several successive days may be 

 carried on. The cylinder is of larger size than in the largest Guddan instru- 

 ment, but can be further enlarged, if necessary, so as to enable sections of the 

 entire human brain to be made. 



3G34b. Freezing Microtome, for enabling the raicroscopist 

 to make thin slices of soft tissues. Invented by Professor Ruther- 

 ford ; made by the exhibitor. ; Gairdner, Edinburgh. 



The freezing microtome was devised by Professor Rutherford for the pur- 

 pose of enabling the microscopist to make thin sections of soft tissues and 

 organs. The tissue is placed in the well ; a strong watery solution of gum 

 arable is poured around it, and a freezing mixture of ice or snow and salt is 

 placed in the [box. The sections are made with an ordinary razor. A full 

 description is given in Rutherford's " Outlines of Practical Histology." 

 (Churchill, London, 1875.) 



3635. Smith's Microtome, modified by Schiefferdecker. 



f\ Majer, Strassburg. 



3636. Tin Mould, for fixing preparations in an embedding 

 mass. F. Majer, Strassburg. 



3637. Microscopical Cutting Apparatus, for soft objects. 



Prof. Jessen, Eldena, in Pomerania. 



3638. Fluid for keeping Parts of Plants, and preserving 

 their colours in glass vessels. 



Prof. Jessen, Eldena, in Pomerania. 



3639. Warm Moist Chamber, for observing microscopical 

 objects at an elevated temperature during long periods of time. 

 (Exhibitor's construction.) 



Prof. Dr. Ferd. Cohn, of the Institute of Vegetable Phy- 

 siology in the University of Breslau. 



The apparatus in question combines the advantages of the moist chamber 

 and the warm stage of the microscope. The object is laid in a drop of water 

 on the underside of the glass plate in the centre of the cover, which has 

 been previously removed ; the cover is then firmly fixed, and the whole 

 apparatus placed on the stage of the microscope. 



It is warmed to the desired temperature, which is indicated by a thermo- 

 meter, by means of a small gas flame placed underneath the descending 

 heating tube. The object is observed through the glass plate in the cover. 



