60 VETERINARY BACTERIOLOGY 



C 6 H 12 O 8 + Zymase = 2C 2 H 5 OH + 2CO 2 4- Zymase. 



Dextrose. Alcohol. Carbon 



dioxid. 



Although alcohol and carbon dioxid represent the end-products, 

 it is by no means certain that intermediate hydrolytic products 

 are not formed, and this splitting action may be essentially hydro- 

 lytic. Reducing enzymes have also been demonstrated in plant 

 and animal tissues and undoubtedly occur in microorganisms. 



The autolytic (Gr. auto, self, lyo, dissolving) enzymes de- 

 serve particular mention. Enzyme's are known to occur in 

 most animal and plant cells that will, at least partially, digest 

 the cells in which they occur. The rigor mortis or stiffening of the 

 tissues of an animal after death is due to such an autolytic enzyme 

 which coagulates the muscle protoplasm. The softening of the 

 tissues which occurs later, the so-called " ripening " of meat, is due 

 in part to the action of another proteolytic enzyme which carries the 

 digestion somewhat further. Microorganisms contain such en- 

 zymes, and when the cells die, as in an old culture, they are then 

 partially digested. This autolytic action we shall find to be of 

 some practical significance in a discussion of disease production 

 and immunity, as by it certain poisonous substances may be 

 released from the cell. 



