REMARKS UPON THE METHODS. 235 



bodies are formed by the action of dilute sulphuric acid upon unde- 

 composed albuminous substances, and they recommend the employ- 

 ment of the Stas-Otto method with these conditions : (1) No more 

 acid should be added than is absolutely necessary to keep the reac- 

 tion acid ; (2) the heat used in evaporation should not be great, and 

 it is better that evaporation should be made in vacuo. In this way, 

 they say, no basic substance will be obtained from fresh tissue. 



Marino-Zuco ascertained that by treating fresh eggs, brain, liver, 

 spleen, kidney, lungs, heart and blood by either the Stas-Otto or the 

 Dragendorff method, he could obtain a substance which gave alka- 

 loidal reactions, and which he demonstrated to be cholin. His ex- 

 periments led him to believe that cholin does not exist preformed in 

 these fresh tissues, but that it results from the action of the dilute 

 acids upon lecithin. Cholin was found most abundantly in those 

 tissues which are rich in lecithin, such as the yolks of eggs, brain, 

 liver and blood ; while only traces could be obtained from the whites 

 of eggs, lungs and the heart. The method of Dragendorff was found 

 to furnish much larger quantities of cholin than could be obtained by 

 the Stas-Otto process. Coppola agrees with his countrymen in con- 

 demning the method of Dragendorff as a means of extracting pto- 

 mains. However, the Stas-Otto method is by no means perfect, and 

 the principal difficulties met with in its application are as follows : 

 (1) In most instances the extraction of the base is incomplete ; (2) 

 the degree to which the putrefactive alkaloid is removed by the sol- 

 vent depends largely upon the nature of the other substances pres- 

 ent. This fact in some cases aids and in others hinders the labors 

 of the investigator ; thus, several ptomains, which when pure are 

 wholly insoluble in ether, may be removed in part, at least, from or- 

 ganic mixtures by this solvent by passing into the solution along 

 with other substances ; but if the attempt be made to purify one of 

 these bases by repeated solution and extraction with ether, the re- 

 sult is failure, because the more completely the alkaloid is freed from 

 impurities, the less soluble in ether it becomes. This criticism is 

 equally applicable to the Dragendorff method, and to all others in so 

 far as extractions are made. However, we may state that the Stas- 

 Otto method is in suitable cases the best that can be employed. By it 

 the substances are submitted to the least chemical manipulation, and 

 the results obtained are the most reliable. Many of the more com- 

 plex putrefactive products are so easily decomposed or otherwise al- 

 tered that the investigator should seek to isolate them by the sim- 

 plest methods possible. If it can be done without the addition of any 

 acid or without the application of heat, so much the better. 



By his method, Brieger discovered a number of basic bodies, and 

 gave great impetus to the study of the chemistry of putrefaction ; 

 but it is open to the objection that basic substances may be formed 

 by the action of the reagents used, and Gram states that when the 



