INTRODUCTION V 



An extremely fine chrome yellow may be made by dissolving 

 200 parts of acetate of lead and 105 parts by weight of chromate 

 of potash in separate dishes of water. After complete solution 

 mix and allow the precipitate to settle. Pour off the supernatant 

 fluid and wash the precipitate with several waters so as to remove 

 the potassium acetate which would injure the specimen. 



Many instruments syringes, water-pressure apparatus, etc., 

 have been proposed for injecting, but a considerable experience 

 has led to the conclusion that for small animals there is nothing 

 better than a large rubber bulb for the pressure. This is con- 

 nected by rubber tubing with the canula which is inserted in the 

 vessel to be filled. Use the largest canula possible and keep it 

 free from precipitated mass. 



SKELETONS. The skeletons made by the average student are 

 likely to be imperfect, but the knowledge which he obtains in. 

 preparing them is of value. The laboratory should have skeletons 

 well prepared, but the student should clean those which he studies. 

 In the case of fishes it is sufficient to remove the skin from the 

 body, next to place the animal for a few minutes in water 

 near the boiling-point, and then to remove the flesh by hand. 

 With other animals the tissues are more resistant, and in these 

 cases the animal, after removal of the skin, should be boiled in a 

 soap solution made as follows : 



Thoroughly mix with heat 75 grams of hard soap, 12 grams 

 of potassic nitrate (saltpetre), 150 cc. of strong ammonia, and 

 2000 cc. of soft water. For use, one part of this 'stock' is diluted 

 with three of water and the body is boiled in this, the length of 

 time varying with the size and consistency of the animal, care 

 being taken not to boil it long enough to soften the ligaments 

 unless it be desired to separate the bones from each other. 



For decalcification of skull* in order easily to get at the 

 brains, nitric alcohol, made by mixing equal parts of ten per cent 

 nitric acid and ninety-five per cent alcohol, is useful. 



Material for dissection can be obtained from 



Supply Department, Marine Biological Laboratory, Woods 



Hole, Mass. 



Dr. F. D. Lambert, Tufts College, Mass. 

 H. H. and C. S. Brimley, Raleigh, N. C. 

 H. A. Ward, Rochester, N. Y. 

 Kny-Scheerer Co., 225 Fourth Ave., New York. 



