306 SUMMARY OF CURRENT RESEARCHES RELATING TO 



marked, his metliod frequently gives rise to a great number of air- 

 bubbles in the imbedding mass. Consequent upon the altered mani- 

 pulations of Prof. Thoma, we have to adajjt the imbedded specimen 

 to a cork for the purpose of cutting. This may be done in the fol- 

 lowing way. The even surface of the cork is covered by a thick 

 layer of celloidin solution. This is allowed to dry up perfectly, so 

 as to produce a bard membrane of celloidin. This is again covered 

 with further celloidin solution. In the meantime the lower surface 

 of the imbedding mass is cut even, and wasbed with absolute alcohol, 

 and subsequently moistened with a drop of ether. This moist 

 surface is adapted to the stratum of liquid celloidin on the cork, and 

 exposed for a few minutes to the open air. After this the whole is 

 placed in dilute alcohol, which in a few hours will unite the imbed- 

 ding-mass solidly with the cork. 



In a great number of cases it may be regarded as a great advan- 

 tage of the celloidin that it penetrates the tissues thoroughly, and 

 yet remains pellucid, so as to be more or less invisible in the specimen. 

 This quality can be made use of in another direction for the purpose 

 of soaking specimens which are too brittle to be cut after hardening 

 alone. We may make use of celloidin in a similar way to the gum 

 arabic mentioned above. The minute normal and pathological anatomy 

 of the lung in particular will derive great advantage from such a pro- 

 ceeding. Indeed, we are not able to get a perfect idea of the changes 

 produced by pneumonia if we do not by this method or by the fol- 

 lowing (with paraffin) prevent the loss of a great part of the exuded 

 substances which in this disease lie loose in the alveolar cavities. 

 The study also of micro-organisms in the lung will derive great 

 benefit from the celloidin method, and it will be very welcome to 

 many to know that the tissues imbedded in celloidin may be stained 

 with the different fluids, ammonium-carmine, alum-carmine, borax- 

 carmine, hfematoxylin, anilin colours, and various others. The re- 

 action of acids and alkalies, particularly acetic acid and solution of 

 potash, is, moreover, not interfered with. And, further, we are able 

 to colour the object before imbedding with all staining fluids which 

 are not soluble, or only little soluble, in alcohol and ether. 



After staining and cutting, the sections may be mounted in glycerine 

 and various other fluids. Mounting in Canada balsam requires, how- 

 ever, some precautions on account of the chemical character of the 

 celloidin. Absolute alcohol and oil of cloves should be avoided and 

 replaced by alcohol of 96 per cent., and by oleum origani. This is, 

 at least the advice of Schiefferdecker, and Professor Thoma has had 

 no occasion to be dissatisfied with the result. 



The efforts of Biitschli and Blochmann * have given us another 

 splendid imbedding mass, paraffin dissolved in chloroform, which 

 admits of sections of the highest delicacy. Biitschli was able to cut 

 in this imbedding substance small specimens down to • 002 mm. This 

 method seems jjarticularly adapted to researches in embryology and 

 zoology, where hitherto imbedding masses formed of paraffin and 

 turpentine have been frequently used. 



* Biol. Centralbl., i. (1881) pp. 591-2. See this Journal, ii. (1882) p. 708. 



