59 SUMMARY OF CURRENT RESEARCHES RELATING TO 



acetic acid, bichloride of mercury, alcohol, etc., be used, the cells must 

 be previously washed with physiological salt solution, and, after sedimen- 

 tation, the supernatant fluid decanted off. The deposit is then fixed. 

 When the elements are scanty, as in urine, pleural fluid, etc., they must 

 be concentrated by centrifuging before being fixed. In the case of 

 cells not naturally dissociated, e.g. of the liver, spleen, bone-marrow, 

 etc., they may be dissociated first and fixed afterwards, or vice versa. 



The next step consists in washing the fixed cells in a centrifuge, and 

 this operation may be repeated once or twice. 



The third step is to dehydrate the sediment by dropping in absolute 

 alcohol, and after this an equal quantity of anhydrous ether, shaking 

 or inverting the tube from time to time. 



The fourth step is to add some few drops of collodion solution, and 

 then shake the mixture again. 



Fifth step : with a thin dry pipette draw up some of the collo- 

 dionised fluid and place droplets on cover-slips. While the films are 

 still moist, transfer the cover-slips to 80 p.c. alcohol. The preparations 

 are next passed through GO p.c. alcohol and then to water. After this, 

 the treatment is the same as for ordinary histological sections stuck on 

 a slide. 



(3) Cutting, including- Imbedding 1 and Microtomes. 



Rapid Method of Hardening and Paraffin Imbedding.* — The 

 following are the steps in a method employed by 0. Lubarsch by means 

 of which hardening and imbedding are accomplished in from 1 to 3 

 hours, enabling perfect sections to be cut and all stains to be used with 

 success: (1) Blocks of tissue 0'5 cm. thick are placed in 10 p.c. 

 .formalin for 10 to 15 minutes, with one to two changes; (2) 90 to 

 •95 p.c. alcohol for 5 to 10 minutes, with one change ; (3) absolute 

 alcohol for 10 minutes, with two changes ; (4) anilin oil, to clear, for 

 10 to 30 minutes, according to size of block of tissue ; (5) xylol, to 

 remove oil, for 10 to 20 minutes, with two to three changes ; (6) paraffin 

 for 10 to GO minutes. All the steps of the process are carried out in a 

 paraffin oven at 50° C. to 53° C. 



Rapid Hardening and Imbedding.! — A. Stein gives the following 

 modification of Lubarsch's method of rapidly hardening and imbedding 

 fresh tissue : 1. Immersion in 10 p.c. formalin (5 minutes). 2. 95 p.c. 

 alcohol (5 minutes). 3. Absolute alcohol, two changes (10 minutes). 

 -4. Anilin oil, till quite cleared up (15 to 20 minutes). 5. Xylol, two 

 to three changes (15 minutes). G. Paraffin (10 to 30 minutes, accord- 

 ing to the size of the piece). The first four stages are made in in- 

 cubator at 50° to 52° C. ; the last two at 58° to 60° C. 



Zl Use of Radium in Section Cutting. J — H. H. Dixon remarks that 

 every one who cuts paraffin sections is frequently troubled by their 

 electrification, which makes them stick to the knife or curl up and, even 

 when successfully removed from the knife, fly about in an erratic 

 manner. These undesirable phenomena may be completely obviated 



* 



Deutsche Med. Wochenschr., No. -IS (1903) p. 890. 

 t Op. cit., xxix. (1903) p. 806. t Nature, lxx. (1904) p. 198. 



