ABDERHALDEN'S SERODIAGNOSIS OF PREGNANCY 275 



The tissues are first cut into small pieces and thoroughly washed until they are 

 white, as in the preparation of tissues for the dialyzation method. 



The tissue is freed of any excess of water by pressing it through several layers of 

 filter-paper, and the process of hydrolysis is begun. If a larger quantity of the same 

 tissue is to be collected, the pieces are prepared as they are secured by washing them 

 free from blood, boiling in water for ten minutes, and preserving in a stock jar con- 

 taining sterile water and chloroform, and covered with toluol. The tissues are boiled 

 in order to destroy the cell ferments and to prevent autolysis. 



The tissues are now weighed, placed in a large flask, and treated with three 

 volumes of cold 70 per cent, sulphuric acid. The flask is well shaken and carefully 

 stoppered, and placed aside at room temperature (not higher than 20 C.) until the 

 tissues have gone into solution. The flask is shaken occasionally. Solution is 

 usually completed within three days. The flask is now placed in iced water and 

 treated with 10 volumes of distilled water added slowly so that the temperature 

 does not rise above 20 C. 



The sulphuric acid is now precipitated with pure crystallized barium hydroxid 

 until the solution gives no precipitate with either the hydroxid or sulphuric acid. 

 A precipitate of a barium salt of peptones may appear in spite of the fact that no 

 sulphuric acid is present. This precipitate is soluble in nitric acid, whereas barium 

 sulphate is not soluble. The neutralization point is controlled with litmus paper. 

 Small portions are then filtered through filter-paper and tested, first with barium 

 hydroxid and then with sulphuric acid. If a turbidity develops on testing with the 

 barium hydroxid, nitric acid is added and the whole gently warmed. If the pre- 

 cipitate persists, it is evident that more barium sulphate should be added. The 

 final neutralization is effected with dilute sulphuric acid and barium hydroxid. 

 When the solution is free from sulphuric acid, the precipitate of barium sulphate is 

 secured by filtering through filter-paper or by centrifugalization. It is then worked 

 up in a mortar with distilled water and again filtered. It is well to repeat this wash- 

 ing once more. 



The peptone solution is now concentrated in a special apparatus that permits 

 evaporation of the solution under diminished pressure and at 40 C. A special drop 

 funnel delivers the peptone solution drop by drop and thus prevents foaming. 



The yellowish, syrupy residue that remains is covered with 100 volumes of 

 methyl alcohol and boiled. The boiling hot solution is then filtered through five 

 thicknesses of filter-paper into five volumes of cold ethyl alcohol, which is kept in 

 ice water. Precipitation may be accomplished by the addition of ether. Just as 

 soon as the precipitate has formed it is filtered out, preferably through a porcelain 

 filter. The filter is then placed in a vacuum desiccator, and after one or two days 

 the peptone is dry and easily removed and weighed. 



A 10 per cent, solution in 0.9 per cent, salt solution is prepared, and the rotation 

 determined. If the rotation is more than 1, the solution is diluted until the rota- 

 tion is 0.75. 



Testing the Peptone. One cubic centimeter of fresh, clear, hemo- 

 globin- and corpuscle-free serum from a man and an equal amount of a 

 5 to 10 per cent, solution of the peptone are placed in a sterile polaris- 

 cope tube, warmed to 37 C., and the rotation read. If marked changes 

 occur, the peptone is not free from sulphuric acid or barium hydroxid. 

 With the serum of pregnancy, readings should be taken each hour for 

 six hours, and then at intervals of from thirty-six to forty-eight hours. 



