APPENDIX. 109 



The process of maceration may be materially hastened by using warm water instead of cold ; this method 

 should, however, be adopted with caution, as the parts rarely hold together so successfully as under the first- 

 named treatment.* 



When careful preparation of both bony and cartilaginous parts is needed, as in the case of the skull figured 

 in this work, the only reliable method is that of dissecting away the soft parts under water, preserving the 

 whole in spirit as in the case of an ordinary dissection. 



G. By far the most successful preservative fluids for histological work are alcohol and picric acid ; of the 

 latter, either a cold saturated solution or Kleiiienberg's preparation will suffice for the purposes of this work.f 



The tissue to be preserved should be removed from the body as soon as possible after death, cut up into 

 small pieces, and put at once into the preservative medium. For most tissues six to eight hours' immer- 

 sion will be found to suffice, after which the preparation must be transferred to alcohol of gradually increasing 

 strength, viz., 50 p.c., 75 p.c., methylated spirit, and absolute alcohol. Should any excess of acid be present, as 

 can readily be seen from the colour of the spirit, the latter must be repeatedly renewed until it is removed. 

 When this stage is reached the tissue is ready for cutting, and if preserved longer should be kept in 

 absolute alcohol. 



Where the tissues are transferred at once from the body to alcohol, the method of treatment should also 

 be as above stated ; if osmic acid is used, the preparation should be transferred from it to 50 p.c. alcohol, as 

 soon as it begins to assume a black tint. The requisite length of exposure to osmic acid will be found to vary 

 for different tissues, and experience alone can enable the student to use this reagent with success. Where 

 decalcifieation is necessary, the tissue to be operated upon should be placed for twenty-four hours in ^ p.c. 

 solution of chromic acid, then for a similar time in 1 p.c. solution, this being either renewed or replaced by a 

 still stronger when necessary. Decalcifieation completed, the tissue must be transferred to alcohol as above. 



For purposes of staining there is no reagent which gives such uniformly good results as Grenadier's 

 solution of borax carmine. The preparation may be allowed to remain in this for a couple of days, without 

 fear of overstaining. When stained, it should be again transferred to methylated spirit and absolute alcohol, 

 before imbedding, in order that any water or excess of staining fluid may be got rid of. 



Imbedding. The best imbedding material is paraffin, preferably that which shall melt at from 50 3 

 to 60 C. 



A block of this substance of the calibre of a candle, and about an inch and a half in length, will suffice 

 for all requirements here needed. A pit should be made at one end, large enough to take the prepara- 

 tion with case. The preparation, previously soaked in turpentine to saturation, should be first transferred to 

 paraffin, the temperature of which must not exceed that of its melting-point, and allowed to remain in the 

 same until permeated thereby ; it must next be finally transferred to the block prepared to receive it, and 

 completely covered in paraffin, the whole being then allowed to cool. 



Section cutting. For the purposes of this book an ordinary razor will suffice with which to cut sections ; 

 but where a successional series of slices are required, recourse must be had to one of the many microtomes now 

 in use. 



Before cutting the sections, it is desirable to remove as much of the imbedding material as possible from 

 around the preparation. 



When once mastered, the following is the least laborious of all methods of cutting and mounting. 



The results of a long experience, in this and other matters which pertain to the preparateur's art, will be found embodied 

 in Wilder and Gage's "Anatomical Technology," New York and Chicago, 1882. 



t The mode of preparation of these and other preservative and staining reagents, will be found fully stated in Huxley and 

 Martin and other similar works, and the student will find of great service a list of those reagents which have yielded such 

 admirable results in connection with the zoological station, Naples. See Jour. R. M. Soc., Series 2, vol. ii., 1882. 



