that worms which are not attacked by trypsin are digested by this enzyme when they are cut into small pieces; although the pieces of course contain the antienzyme. The other suggestion that a membrane impermeable for trypsin protects the cells would explain why living protozoa are not digested by trypsin, but it leaves another fact unexplained, namely, the autodigestion of all the cells after death by enzymes contained in the cells themselves. [294] Fermi, C., _Centralbl. f. Bacteriologie_, Abt. 1, 1910, lvi., 55. 2. The disintegration of the body after death is not caused exclusively or even chiefly by the digestive enzymes of the intestinal tract or the micro-organisms entering the dead body from the outside, but by the enzymes contained in the cells themselves. This phenomenon of autolysis[295] was first characterized by Hoppe-Seyler.[296] All organs suffering death within the organism, in the absence of oxygen, undergo softening and dissolution in a manner resembling that of putrefaction. In the course of that process, albuminous matter gives rise to leucin and tyrosin, fat to free acids and soaps. This maceration, identical with the pathological conception of softening, is accomplished without giving rise to ill odour and is a process similar to the one resulting from the action of water, acids, and digestive enzymes. [295] Levene, P. A., _Autolysis_. The Harvey Lectures, 1905-1906, p. 73, gives a full account of the work on this subject up to 1905. [296] Hoppe-Seyler, F., _Tübinger med.-chem. Untersuchungen_, 1871, P. 499. In work of this kind, rigid asepsis is required to exclude the possibility of bacterial infection and this was first done by Salkowski, who showed that in aseptically kept tissues like liver and muscle the amount of substances that can be extracted with hot water increases considerably. By the work of others, especially Martin Jacoby and Levene, it was established that the power of self-digestion is shared by all organs. Analysis of the products of the autodigestion of tissues shows that, _e. g._, the amino acids, which constitute the proteins, are produced. Dakin, Jones, and Levene demonstrated the hydrolytic products of the nucleins, in the case of the self-digestion of tissues.[297] [297] Levene, P. A., _Am. Jour. Physiol._, 1904, xii., 276.