BY R. VON LENDENFELD, PH.D. 33 



The sections are placed on the slide as soon as the shellac film is 

 dry and the whole slide then placed in the water-bath stove, where 

 it is just so much heated as necessary to soften and partially melt 

 the paraffin and to soften the shellac, about 55° — 60° C. A.S 

 soon as the paraffin has melted, the slide is immersed in a flat 

 dish, filled with spirits of turpentine. The sections adhere in con- 

 sequence of the shellac to the slide, the turpentine dissolves and 

 removes the pai'affin. The slide can be taken out of the turpenine 

 bath at convenience, but with great care so as not to create a 

 strong current of turpentine on its surface, which might wash some 

 of the sections off and so spoil the series. 



If staining is not required, the sections are now ready for 

 mounting in Canada balsam. The best way is to drain off the 

 turpentine by holding the slide upright and wiping the margin, 

 then to ])ut drops of a Canada balsam or Damar resin on the sections 

 and finally to cover with the cover glass. 



Caldwell and others use slides 6x2, with cover glasses of 

 exceeding thinness and nearly equal size, which I can warmly 

 recommend. 



The ordinary cover glasses o ;, sale here, are much too small and 

 much too thick for any fine work. 



The Canada balsam or Damar resin, the latter is to be preferred 

 on account of its white colour, should be dried in the oven but not 

 heated above 75° to prevent the Canada balsam from turning 

 brown, which it invariably does if heated too much. When 

 dry, brittle and hard, the resin or Canada balsam, is dissolved in 

 chloroform. A mixture of 50 % Canada balsam or Damar and 

 50 % chloloform has the most convenient consistence, and will get 

 hard in an hour on the outer margin and never cracks. 



The mounted sections should be left until the free margin ot the 

 resin has consolidated and then they can be examined. 



As a hint to beginners, I would add, never omit to let the 

 sections pass under a low power both at the beginning and at the 

 termination of the examination. 

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