THE PREPARATION OF MATERIAL. 287 



auricle into their bases. Inject the portal vein and its branches 

 through a small cannula posteriorly directed into the slit previously 

 made to let out the blood. 



XIV. On Preparing Skeletons. The cleaning of bones is not 

 attractive work, but it is made comparatively an easy matter by the 

 process described below (taken from Wilder and Gage's "Anatomical 

 Technology"), and the intrinsic value for study of the disarticulated 

 skeletons thus secured makes it well worth while. There is much 

 that can be learned, too, as easily in the preparation of a skeleton 

 as in any other way, of the relations of the bones to each other and 

 to the muscles and tendons. 



The " liquid soap " used in this process is made by mixing and 

 liquefying : 



Rain water 2000 cubic centimeters. 



Strong ammonia ..... 150 cubic centimeters. 



Saltpeter 12 grams. 



White soap (hard) 75 grams. 



The process consists in (1) removing the skin, viscera, and the 

 greater part of the muscles from the skeleton ; (2) boiling the skele- 

 ton for forty minutes in a mixture of liquid soap one part, and water 

 four parts; (3) boiling the skeleton again for thirty minutes in a 

 mixture of equal parts of liquid soap and water; and (4) cooling the 

 skeleton by immersing in cold water, and cleaning, rinsing, and dry- 

 ing the bones. The time of boiling here given is about the time 

 required in the preparation of a rabbit skeleton. Less time will be 

 required to complete the boiling of smaller skeletons. 



XV. On Cheap Apparatus. In addition to the pieces of simple appa- 

 ratus mentioned in the text, the following are given as having proved 

 serviceable : 



Dissecting needles may be made by pushing with pliers the eye end 

 of common sewing needles into wooden handles. 



A simple forceps, which the author has often preferred to use in the 

 handling of minute objects, is made by trimming a narrow strip of 

 sheet brass or tin to a point at each end, and bending the points to- 

 gether and parallel. 



Bristles of the ordinary sort, obtainable from a harness maker, may 

 be tipped with paraffine or sealing wax. 



Ordinary earthenware jars of several gallons' capacity serve well as 

 receptacles for organic refuse in the laboratory. 



A serviceable net for collecting fresh-water sponges by scraping sub- 

 merged timbers is made by attaching a circular wire frame to the back 



