222 PHARMACEUTICAL BACTERIOLOGY 



3. Lysins. — These will be discussed under immunity from disease. 

 Though these cell, germ and blo6d corpuscle destroying agents found 

 in the serum of the blood and in tissue cells, are not generally clasrsed 

 as ferments, they have many of the characteristics of the proteolytic fer- 

 ments pepsin and trypsin. Three kinds of blood lysins have been studied, 

 bacterolysins which actively destroy bacterial cells, hemolysins which 

 actively destroy red blood corpuscles and cytolysins which actively de- 

 stroy tissue cells. They are all specific in nature as will be explained 

 elsewhere. 



4. Opsonins. — These agents found in the blood and in tissue cells 

 will be more fully described elsewhere. Like the lysins they are specific 

 in action and their enzyme-like nature is rather problematical. 



5. Papain. — -This is a proteolytic ferment found in the fruit of Carica 

 papaya, having a very marked action on meats. It was used by the natives 

 of Brazil as an aid in preparing meat. Its action is closely similar to that 

 of pepsin. Papain is a well-known commercial product used in defective 

 stomach digestion and also for the purpose of peptonizing meats. It does 

 not attack living protoplasm hence it is non-toxic. A papain-like ferment 

 is found in the fig, in the pineapple (bromelin), in cucumbers and in other 

 plants. 



6. Of Ductless Glands. — The ductless glands of the body contain certain 

 substances of an enzyme-like nature which are found useful in the treatment 

 of disease. The commercial articles made from these glands (adrenaUn, 

 desiccated thyroid glands, etc.) are fully described in standard works on 

 materia medica and in dispensatories, to which the reader is referred. 



7. Of Insectivorous Plants. — Certain plants (Drosera rotundifolia, Nep- 

 enthes gracilis, N. hybridus, Dioncea muscipula, Aldrovandia vesiculosa, 

 Utricularia vulgaris and Darlingtonia Californica) secrete a pepsin-like 

 ferment. At one time it was supposed that bacteria symbiotically as- 

 sociated with the insectivorous plant hosts secreted the proteolytic en- 

 zyme, but this theory has recently again been questioned. There is, 

 however, no doubt that the plants named have the power of digesting and 

 assimilating animal substances. 



8. Of Cryptogamous Plants. — Proteolytic ferments are found in some 

 of the fungi as PenicilUum, in Aspergillus niger, Agaricus and in Fuligo 

 septica. Similar ferments are found in many different species of bacteria 

 as anthrax bacillus, cholera bacillus, Bacillus mesentericus vulgatus, 

 tubercle bacUlus, sarcina and others. Some of these bacterial ferments 

 behave hke exotoxins in that they are absorbed into the culture media in 

 which the bacteria are grown. Many bacteria have the power of liquefy- 

 ing gelatine. Some of the yeasts form proteolytic enzymes. 



9. Seed Ferments. — Proteolytic ferments are widely distributed in 



