370 SUMMARY OF CURRENT RESEARCHES RELATING TO 



least 12 hours, then for another 12 hours in a saturated solution of 

 paraffin in ligroin or tetrachloride. These preceding stages are carried 

 out at room temperature. The pieces are now placed in a thermostat 

 at 58° for about half an hour, and then transferred to liquid paraffin 

 (melting-point 54°-5G°). The last step is repeated, and then after 

 about 3 to not more than 6 hours the preparations are imbedded 

 in paraffin (melting-point 54°-50°). The blocks obtained by this method 

 allow very satisfactory sections to be cut from them, and crumpling is 

 slighter and less frequent than by the ordinary imbedding methods. 



Carbon tetrachloride as a Clearing Fluid.* — J. Plecnik points to 

 the inflammability of carbon bisulphide as a great objection to its use 

 as the clearing medium for tissues that are to be imbedded in paraffin, 

 and also mentions the fact that it causes disintegration of nuclei stained 

 with osmium. 



The author tried petroleum-ether for the purpose, but found that 

 though better in some respects, it was equally inflammable and did not 

 yield such easily cutting tissues as carbon bisulphide. He therefore 

 advocates the employment of carbon tetrachloride as the clearing 

 medium in such cases, as it is not open to either of the objections urged 

 against carbon bisulphide, nor does it interfere with the easy cutting of 

 thin sections from the imbedded tissues, though the results are not quite 

 so satisfactory as with carbon bisulphide. 



C4) Staining: and Injecting - . 



Differential Stain of B. Diphtherial — J. W. Peck suggests the 

 substitution of Loeffler's (alkaline) methylen-blue for the acetic acid 

 methylen-blue usually employed in Neisser's differential method. The 

 author states that it is more reliable in swabbings and in cultures, shows 

 tie differential staining equally well in recent and in old cultivations, 

 and, moreover, has the advantage of never staining either the bacillus 

 of Hoffmann or the B. coryzcc segmentosus. 



Flagella Staining.^ — G-: de Rossi cleans the cover-glasses with 

 alcohol, then puts them for 10 to 15 minutes in boiling sulphuric acid, 

 washes repeatedly in water, immerses in a mixture of equal parts of 

 alcohol and benzin, wipes them with a clean cloth, and finally flames 

 them 40 to 50 times over a Bunsen burner. The films should be made 

 from agar cultures 8 to 12 hours old at 37°, or 18 hours old at 15° to 

 20°. Before using a culture it should be examined in a hanging-drop 

 in order to ascertain if the bacteria are sufficiently motile. If so, then 

 a particle from the culture is removed by means of a platinum loop, 

 and mixed with a droplet of water on a slide. From the emulsion a 

 loopful is removed to a watch-glass, in which has been placed some 

 10 to 15 drops of distilled water. After stirring the emulsion and the 

 water up together a little drop is removed on a loop and placed on the 

 centre of a cover-glass. It is not spread out, but is allowed to dry in 

 the air or in an exsiccator. The films are not fixed. For the staining 

 three solutions are required : — (A) consists of 50 grm. pure carbolic 



» Zeitschr. wiss. Mikr., xix. (1903) pp. 328-9. f Lancet, 1903, i. p. 92. 



I Centralbl. Bakt., l te Abt. Orig., xxxiii. (1903) pp. 572-6. 



