Abstract
Toxins, ferments, and protein solutions have been filtered through collodion membranes by many investigators but the results have varied to a considerable degree. The following experiments may explain this variation.
Collodion sacs were made and mounted on glass tubes, according to the Novy technique. Before filtration, the empty sacs were immersed in water and submitted to air pressure (three inches of mercury); if perfect, they were then used. The filtration was done under a 2-inch vacuum. After the filtration the sacs were again retested by air pressure. If still perfect, the filtrate was then used for experimentation.
In this manner diphtheria toxin was filtered. One hundredth of a cubic centimeter of this toxin killed a guinea-pig in 39 hours. Three cubic centimeters of the undiluted toxin were filtered through a collodion sac, and one hundredth of a cubic centimeter of this filtrate killed in 38 hours, none of the toxin having been held back by the filter. However, if the toxin was diluted, 1 to 100 before filtration, one cubic centimeter of the filtrate failed to kill, causing only slight induration.
Get full access to this article
View all access options for this article.