464 THE ANIMALS AND MAN 



arations of French gelatine, but white glue will answer 

 most purposes. For fine injection use a combination of 

 the following: i part of a solution of gelatine, i part to 

 4 parts of water; i part of a saturated solution of lead 

 acetate in water, and i part of a saturated solution of potas- 

 sium bichromate in water. A mixture of these when hot 

 gives a beautiful yellow injection-mass which, filtered, will 

 pass through the finest capillaries. For different colorings 

 use dry paints, which come in ultramarine blue, vermilion, 

 and green. The gelatine should be thoroughly soaked 

 before the coloring-matter is added. A mistake is generally 

 made in using the injection-mass too thick. One part by 

 weight of gelatine to six or even more parts of water is a 

 good proportion. The gelatine as well as glue-masses 

 should be made in a water-bath, which consists of one dish 

 placed within another outer one containing warm water. 

 The mass should be injected warm, not hot, after which the 

 injected specimen is to be placed in cold water until the 

 injecting-mass has set. Glue (the ordinary white kind) 

 can be used for most injections just as the gelatine was 

 used, but should not be so much diluted. All injection- 

 masses should be filtered through a cloth before using. 



Preparing skeletons. In general, skeletons are best 

 cleaned by boiling. After most of the flesh has been cut 

 away the skeleton should be boiled in a soap solution 

 until the remaining parts of the muscles are thoroughly 

 softened. The soap solution is made of 2,000 c.c. of water, 

 preferably distilled, 12 grams of saltpetre, and 75 grams of 

 hard soap (white). Heat these until dissolved, then add 

 150 c.c. of strong ammonia. This stock solution is mixed 

 with four or five parts of water, when the mixture is ready 

 for use. The bones after boiling are rinsed in cold water, 

 brushed and picked clean, then left to dry on a clean surface. 



Preserving anatomical preparations. Many specimens 

 worth keeping will be found, and for them a solution known 

 as Fischer's formula is suggested as good, especially for 

 brains. Fischer's formula is made up as follows: 2,000 c.c. 

 of water, 50 c.c of formalin, 100 grams of sodium chloride, 



