Journal of Applied Microscopy. 229 



glass. If the siliceous or calcareous nature of the test cannot be determined by 



the eye, resort may be had to chemical means. 



L. C. Glenn. 



Johns Hopkins Geological Laboratory, Jan. 20, 1899. 



A Rapid Method of Paraffin Imbedding. 



This subject has been treated of in numerous magazine articles, appearing 

 from time to time in different journals, and by different writers. These methods, 

 as described by the various authors, take from thirteen to twenty hours in their 

 consummation. 



The method, to be described, is actually rapid, and has the added virtue of 

 being extremely useful for diagnostic purposes ; and the specimens, so obtained, 

 are permanent. 



The method, in detail, is as follows : a piece of fresh tissue, the thickness of a 

 thin or medium microscopical glass slide, is suspended in absolute alcohol, from 

 two, to two and three-fourths hours ; it is then placed in benzol-cedar-wood oil 

 mixture until semi-transparent, and no whitish areas appearing in any part Of it 

 (usually from ten to thirty minutes), the tissue is now put into melted paraffin, 

 heated to not less than 47 degrees C. or more than 50 degrees C. This paraffin 

 is a mixture of one part hard paraffin (50 degrees C. melting point) and two 

 parts soft paraffin (40 degrees C. melting point). The bath, in paraffin, should 

 be prolonged until tRe tissue is opaque, as it was at the end of the alcohol bath, 

 — if it is at all translucent it must be returned to the paraffin bath until opaque. 

 The specimen, at this point, should be carefully watched, as some tissues will 

 begin to shrink as soon as infiltration is complete, and should be removed and 

 imbedded at once. Other tissues, that do not show this tendency to shrinkage, 

 may be left in the paraffin bath indefinitely, without detriment. 



This bath should require from five to thirty minutes. 



The specimen is now imbedded in melted paraffin, of a mixture of two parts 

 of hard and one part of soft, and allowed to cool slowly until semi-solid, when it 

 should be rapidly cooled in ice water. 



Sections are cut ; affixed to slide with Mayer's albumen mixture ; passed 

 through benzine and 90 per cent, alcohol ; stained first with dilute aqueous solu- 

 tion of China blue or Bleu de Lyon, rinsed in water, and then brought into 

 safranin solution, for a few seconds; washed with absolute alcohol, until the blue 

 becomes prominent ; cleared with clove oil and mounted in Canada balsam. The 

 safranin solution is made by adding one part 40 per cent, formalin to four parts 

 of saturated aqueous solution of safranin. 



If a more selective stain is desired, for the demonstration of karyokinetic 

 nuclei the section should first be stained with safranin ; washed lightly in 70 per 

 cent, alcohol, containing .5 per cent, picric acid, and finally in absolute alcohol. 

 The tissue, so treated, may be of any length or width, but must not be thicker 

 than mentioned above. The fixation and hardening is accomplished by the use 

 of a four-ounce bottle, the bottom of which is covered to about an inch in depth 

 with burnt copper sulphate and then filled to the shoulder with absolute alcohol ; 



